sudanglo:
As is usual with problems of translation, it may not be possible to identify a single term as occupying the same semantic territory as the word to be translated, and different solutions in different contexts may be the only possibility.

Indeed. I wonder how many natural languages have single-word equivalents of "underdog", and if so, how varied they are.

I like jefusan's idea of coming at it by means of folkloric symbolism, but it's very hard to find something that will be immediately recognizable.

So far, I like etŝanculo and subŝanculo the best, and I'm leaning toward subŝanculo, because sub carries the meaning of insufficiency and also the positional meaning of "underness", which is to say, not in a dominant or favored position.

T0dd:

sudanglo:
As is usual with problems of translation, it may not be possible to identify a single term as occupying the same semantic territory as the word to be translated, and different solutions in different contexts may be the only possibility.

Indeed. I wonder how many natural languages have single-word equivalents of "underdog", and if so, how varied they are.

I like jefusan's idea of coming at it by means of folkloric symbolism, but it's very hard to find something that will be immediately recognizable.

So far, I like etŝanculo and subŝanculo the best, and I'm leaning toward subŝanculo, because sub carries the meaning of insufficiency and also the positional meaning of "underness", which is to say, not in a dominant or favored position.

I'm an Argentinian and I really can't think of a translation for "underdog". We even don't have an expression for that!

T0dd:
Indeed. I wonder how many natural languages have single-word equivalents of "underdog", and if so, how varied they are.

It seems that German doesn't really - well, here's the dictionary entry for English "underdog".

German has borrowed Underdog from English. The translations Außenseiter and Verlierer more properly translate to "outsider" and "loser" respectively. The linked dictionary also gives substantivized forms of the adjectives unterdrückt (oppressed) and unterlegen (inferior). None except for the loanword really convey the idea in question - which is probably why German borrowed this word from English.