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BO = "related by marriage", "in-law".

BO mainly appears in the following three family words, and in the three corresponding IN-words:

  • patro (father) → via bopatro (your father in law) = The father of your husband or wife.
  • filo (son) → via bofilo (your son in law) = The husband of your daughter.
  • frato (brother) → via bofrato (your brother in law) = The brother of your wife or husband, the husband of your sister or the husband of a daughter of your wife or husband.

The BO-words bokuzo (cousin-in-law), bonevo (nephew-in-law), boonklo (uncle-in-law), boavo (grandfather-in-law), bonepo (grandson-in-law), boparenco (relative-in-law) and bofamiliano (family member-in-law) (and the corresponding in-forms) are also possible, but seldom used. Instead, the simple words without BO are usually used.

When talking about familial relationships of two marriages, one might logically use a double BO-prefix: via bobofrato = "the husband of the sister of your spouse", via bobokuzo = "the husband of the cousin of your spouse", via bobonevo = "the husband of a nephew or niece of your spouse", via boboonklo = "the husband of an uncle or aunt of your spouse." However, in practice we use only a single BO-prefix for these meanings.

BO can appear together with the prefixes GE and PRA. The reciprocal order of these prefixes isn't important to the meaning, but normally GE is put last: bogepatroj (parents-in-law), bogefratoj (siblings-in-law), prageavoj (great-grandparents), bopragekuzoj (great-cousins-in-law), and so forth.


ĈEF = "the most important, the highest in rank". ĈEF shows that the thing that follows is the most important among all similar things:

  • redaktoroĉefredaktoro = the most important editor (i.e. of a magazine) who is responsible for the magazine's contents. (chief editor)
  • artikoloĉefartikolo = the most important article of the newspaper, normally an article which expresses the opinion of the publisher or chief editor. (editorial)
  • urboĉefurbo = the city which is officially designated as being the most important in the country, and which is normally the seat of government. (capital)
  • stratoĉefstrato = the most important and largest street of the city
  • ĉefo = the most important or highest ranking person; ĉefa = most important, high ranking, main

ĈEF indicates the most important thing or person. The suffix ESTR indicates a person who directs and decides. Often the person who is the most important also has the power of decision and therefore we can sometimes express the same idea using either the suffix ESTR or ĈEF, e.g.: ĉefredaktoro (the most important editor)≈ redakciestro (head of the editorial department). ESTR always indicates a person, while ĈEF as a prefix does not in itself indicate a person: ĉefurbo (capital city) is quite distinct from urbestro (mayor). The independent noun ĉefo (boss) always indicates a person and therefore the words ĉefo and estro are in practice almost synonyms.


DIS = "going out in different or multiple directions; separating". DIS is used only with action words, and always shows the manner of the action or a result of the action.

With a word indicating movement, DIS shows that several things are moving away from one another in different directions:

  • iridisiri = to go off in different directions.
  • kuridiskuri = to run off in different directions.
  • sendadodissendado = sending away in several directions.

When used with a word that already has the meaning of separation, DIS intensifies this meaning:

  • ŝiridisŝiri = by tearing divide into pieces
  • rompidisrompi = to break apart, to break into pieces
  • dedisde = "de" with a meaning of moving away or dissimilarity (here DIS appears as an exception in front of a non-action word)

With a word that has the meaning of combining or bringing things together, DIS replaces the sense of combination with a sense of separation. In this case, DIS is equivalent to MAL:

  • volvidisvolvi = unwind
  • faldidisfaldi = to unfold

DIS is also used as an ordinary root: disa = separated, divided, loose; disigi = to cause to come apart, to divide.


EK = "beginning of an action, sudden action". EK is only used with words indication action, and always shows the manner of action.

EK is usually used to show that an action begins. It shows the very first moment of the action, often with a nuance of suddenness or unexpectedness:

  • kuriekkuri = to start running
  • sidieksidi = to sit down (to start sitting)
  • pluviekpluvi = to start raining
  • florofloriekflori = to start flowering
  • deekde = beginning of (here, as an exception EK appears before a non-action word)

In some cases, the suffix can also show the beginning of an action: sidiĝi (to sit down), estiĝi (to come into being), and so forth. EK shows a quicker, more sudden beginning than IĜ.

Sometimes EK shows a sudden action that lasts only a moment. In that case, it indicates not only a beginning, but a complete action:

  • fulmiekfulmi = to lighten suddenly as in a flash of lightening.
  • briliekbrili = suddenly and momentarily brighten
  • rigardoekrigardo = a rapid sudden look (glance)

EK is also used as an ordinary root and as an exclamation:

  • eki = to get started
  • ekigi = to start, to start-off, to cause to start
  • ek! = start now! off you go! let's go!


EKS = "ex-; formerly having a state, that it no longer has". EKS is mainly used to speak of professions and other human roles, but it can also be used for words of other types:

  • reĝoeksreĝo = person who formerly was king, a king who has abdicated.
  • edzoeksedzo = a person, who was formerly a husband (ex-husband)
  • (ge)edziĝieks(ge)edziĝi = to get divorced, to end the marriage
  • modaeksmoda = not stylish anymore, out of style
  • eksa = former, no longer existant

When used with an animal word, EKS has the special meaning of "castrated": bovoeksbovo = a steer (a bull that has been castrated)


GE = "both sexes". GE is used with male and gender-neutral words to give them the meaning of both genders.

GE usually shows a pair:

  • patrogepatroj = parents, father and mother (of common children)
  • edzo (husband) → geedzoj (husband and wife) = husband and his wife.
  • fianĉo (fiance) → gefianĉoj (fiance and fiancee) = fiancee and her fiance.
  • doktorogedoktoroj = a doctor and his/her spouse(gedoktoroj logically would be a couple where both are doctors — therefore nowadays we hardly use words like gedoktoroj when speaking about a couple)

GE is also used with family words to show groups of relatives of both sexes:

  • fratogefratoj = sister(s) and brother(s)
  • filogefiloj = son(s) and daughter(s)

GE is also used in a more general sense to show that both sexes are present in a group:

  • knabogeknaboj = both boy(s) and girl(s)
  • lernantogelernantoj = both male and female pupils
  • doktorogedoktoroj = both male and female doctors

If a word is itself neutral, GE need not be added, unless you wish to emphasize that both sexes are present. Normally, therefore, we say simply lernantoj (pupils, students) and doktoroj (doctors).

In rare cases GE appears before something which itself cannot manifest gender. A GE-word of this kind indicates something intended for both sexes, often with a jocular nuance. These words are outside of the norm, and should not be used too often: lernejogelernejo = a school for both sexes.

Note: GE-words with an O-ending can normally only be plural, because it takes more than one person to represent both sexes. But one sometimes tries to stretch the meaning of GE to mean "either one of the two sexes". Then you can build words like gepatro = "father or mother", geedzo = "wife or husband". This usage, however, is outside of the norm and many believe it to be illogical and incorrect. But these words are understandable and can be quite useful. Time will tell whether or not they become accepted.


MAL = "the exact opposite idea". MAL can be used only with words that have a logical opposite.

  • bona (good) → malbona (bad)
  • granda (big) → malgranda (little)
  • feliĉa (happy) → malfeliĉa (unhappy)
  • laborema (industriuous) → mallaborema (slothful)
  • graso (fat) → grasa (greasy,fatty) → malgrasa = having little fat, (lean)
  • pli (more) → malpli (less)
  • tro (too much) → maltro (too little)
  • fermi (to close) → malfermi (to open)
  • ami (to love) → malami (to hate)
  • ŝlosi (to lock) → malŝlosi (to unlock)
  • aliĝi (to join a group) → malaliĝi (to quit a group)
  • kodo (a code) → kodi (to encode) → malkodi (to decode)
  • antaŭ (in front of) → malantaŭ (behind)
  • supre (above) → malsupre (below)
  • simetrio (symmetry) → malsimetrio (asymmetry)
  • amiko (friend) → malamiko (enemy)
  • lumo (light) → mallumo (darkness)
  • malo (opposite) male (on the contrary)

Sometimes one might hesitate between MAL and ne (not). Ne shows absence, lack of something, while MAL shows the presence of the opposite idea. Often, both can be used, with somewhat differing meanings. At times there is only a nuanced difference. MAL is sometimes used as a stronger ne:

  • laŭdi (to praise) = to say how good something is
  • ne laŭdi (not to praise) = not to say how good something is
  • mallaŭdi (to disparage) = to say how bad something is
  • ne mallaŭdi (not to disparage) = not to say how bad something is
  • amiko (friend) = a person towards whom one feels sympathy or love
  • neamiko = a person towards whom one has no special feelings
  • malamiko (enemy) = a person we find unpleasant or that we hate


MIS = "erroneous, wrong, bad". MIS always shows a quality or attribute of what comes next.

  • kalkuli (to calculate) → miskalkuli (to miscalculate)
  • kompreni (to understand) → miskompreni (to misunderstand)
  • skribi (to write) → misskribi = to write making mistakes
  • korekti (to correct) → miskorekti = to introduce errors while correcting
  • uzi (to use) → misuzi (to misuse)
  • trakti (to deal with) → mistrakti (to mistreat)
  • faro (deed) → misfaro (misdeed)
  • formo (form, shape) → misformo = something deformed or misshapen
  • formi(to form, to shape) → misformi = (to deform, to misshape)

Don't confuse MIS with MAL. MIS doesn't change the basic meaning of a word; it only adds the idea that something is wrong or bad. MAL completely changes the meaning to its logical opposite.

  • laŭdi (to praise) = to say how good something is
  • mislaŭdi = to mistakenly say that something is good, when in fact it is bad.
  • mallaŭdi (disparage) = to say how bad something is
  • mismallaŭdi = to mistakenly say that something is bad, when in fact it's good


PRA = a very long time ago, primitive". PRA shows that what comes next is distant in time:

  • homo (man in the sense of human being) → prahomo = primitive man, hominid species which evolved into homo sapiens
  • arbaro (forest) → praarbaro (primeval forest, old growth forest) = a primitive untouched forest existing from time immemorial.
  • tempo (time) → pratempo = the beginning time of mankind or of the word (primeval times)
  • antaŭlasta (penultimate) → praantaŭlasta = "prior to the penultimate"

On the family words av(in)o (grandmother/father), nep(in)o (granddaughter/son), onkl(in)o (aunt/uncle), nev(in)o (niece/nephew) and kuz(in)o (female/male cousin), PRA shows a relationship of one generation more distant (either earlier or later in time).

  • avo (grandfather) → via praavo (your great-grandfather) = the father of your grandfather or grandmother
  • avo (grandfather) → via prapraavo (your great-great-grandfather) = the father of your great-grandfather or great-grandmother
  • avovia praprapraavo = the father of your great-great-grandfather(mother)
  • nepo (grandson) → via pranepo (your great-grandson) = the son of your grandson or granddaughter
  • nepo (grandson) → via prapranepo (your great-great-grandson) = the grandson of your grandson or granddaughter
  • onklo (uncle) → via praonklo (your great-uncle) = the uncle of your mother or father
  • nevo (nephew) → via pranevo (your great-nephew = son of your nephew or niece
  • kuzo (cousin) → via prakuzo (your second cousin)= the son of the cousin of your father or mother

On the family words patr(in)o (mother/father) and fil(in)o (daughter/son), PRA shows a distant familiar relationship, several or many generations earlier or later:

  • patro (father) → prapatro (forefather) = a male ancestor, a real or imagined founder of a people, tribe or family
  • filo (filo) → prafilo = a distant male relative of is the offspring of a certain person

The expressions prapatroj (great grandfathers) and prafiloj (great grandsons), with a J-ending, are generally used to refer to ancestors and descendants, often without distinguishing between genders.

On words for familial relationships, PRA can appear together with the prefixes BO and GE.


RE = "re-; to come or put something in the same place as abefore, to make or become as something was before, to happen or to do something again in the same or another way". RE is used only with action words, and always shows the manner of the action:

  • veni (to come) → reveni (to come back) = to return to a place where one was before
  • doni (to give) → redoni (to give back)= give something to someone who had it before
  • brilo (gloss, sheen) → rebrilo= a bright reflection
  • bonigi (improve, to make good) → rebonigi= to make good again what had become defective (refurbish, recondition, restore etc)
  • saniĝi (to become healthy) → resaniĝi (to recover = to become healthy again after an illness
  • diri (to say) → rediri = to say the same thing again, to say in answer to (to reply)
  • trovi (to find) → retrovi = to find what one has lost
  • koni (to know, to be acquainted with) → rekoni (to recognize) = On seeing something to note that one already is acquainted with it, to acknowledge or admit the value of something
  • turni (to turn) → returni = to turn again to the previous (opposite) direction
  • ree = again, once more

Some RE-words came into existence due to influence from words used in other languages, and therefore do not have a logical meaning. For example, reprezenti (to represent) ordinarily doesn't mean "to present again", but "to act instead of someone, in someone's name". Resumi (to summarize) isn't "to sum up again", but "to concisely express the essence". These, and other words, are normally regarded as non-compound words (made from the roots REPREZENT and RESUM). Returni and especially returna and returne were previously used to mean "return", with a meaning of going back or giving back. Now, those words are only used when discussing turning something (re-turning).

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