Beginner here, trying to find my way through the grammar. Under konciza/negacio I found the phrase

Neniu leciono nek prelego plaĉis al ŝi. - No lesson or lecture pleased her

I expected Nenia instead of Neniu. Is one of them wrong or is there a difference in the meaning? I consulted other grammars but didn't find anything unambigously conclusive.

The -ia words cover 'quality' while the -iu words are 'individuality'. Often when you use -io words to refer to something, the -iu option would be used instead if you could identify a specific /individual/ or /distinct/ person or thing. Neniu is relating to an (individual) lesson, rather than the quality pleasing her.

The correlatives are essentially grouped as -ia (quality), -ial (motive), -iam (time or duration), -ie (place or location), -iel (manner in which...), -ies (possession), -io (things), -iom (quantity) and -iu (individuality).

When I was learning these things, it was like hitting a brick wall. Was learning at a real pace, then was stumped with them for weeks.

Thanks for the reply. That was helpful.

I assume I'm stumped because I don't know which of these neni-words can be used like an adjective.
I don't think it's all of them. But who knows Wouldn't be the first surprise. Back to studying.

I think that what was most confusing for me for a while is that in English we would use 'none' or 'nothing' in all of these situations where the EO equivalents need to be translated as several words.

Nenie would be 'no place...', neniom would be 'no quantity of...' Etc. and often /all/ have to be read to make a sentence make sense. Yet other times like the neniu example, 'no individual lesson...' could be shortened to 'no lesson...' and still make perfect sense. I do this a lot and therefore confuse myself for the EO translation.

In your sentence both neniu and nenia would be correct. But it slightly changes the meaning if you use nenia.

Neniu leciono plaĉis al ŝi - she liked none of the lessons

Nenia leciono plaĉis al ŝi - there wasn't any type of lesson she liked.

Neniu can be used as an adjective or a noun. It belongs to the small group of words in Esperanto that don't require a grammatical ending, and can often be used in more than one grammatical role.

(NB. Useful phrase: - Mi havas absolute nenian ideon - I haven't got a clue.)

Whether the 'a' in nenia is the adjective ending (or the 'o' in nenio is the noun ending) is debateable

You will probably find it more profitable to think of nenia (and nenio) as stand-alone roots (like neniu) and think of the final letter as a mnemonic device helping you to remember the meaning of nenia (and nenio).

That said, you will come across compound words with neni, for example neniigi (nullify, cancel, destroy) where the neni seems to stand for nenio.

But the ti in tio/tia, the ki in kio/kia, the ĉi in ĉio/ĉia, do not seem to be detachable (ie have not led to compound word formation).

You could always argue that nenio really is neni+o, but that sticks you with the idea the nenie should mean 'in no way' rather than nowhere.

A better solution is to say that nenio is one root (as is nenia also), and to list in the dictionary 'neni' as pseudo prefix, generating a handful of words like neniigi and nenifari.

Sphynx:The -ia words cover 'quality' while the -iu words are 'individuality'.

+1. Great explanation.

nenia = not any kind of something

neniu = not any particular one of something

None of the lessons pleased her
Neniu leciono plaĉis al ŝi

No type of lesson pleased her
Nenia leciono plaĉis al ŝi

When you see iu it is something that can be chosen or it is a selection of something.

You could probably use nenia or neniu in this case but neniu is way better.