Where does the adjective "woch" (tall) come from?
It's introduced in an early lesson, but I can't find it in Okrand's TKD nor KGT.
When you can't find a word in TKD or KGT, go the Klingon Language Institute's list of new Klingon words. This gathers all new words delivered by Okrand in one form or another, and makes a note of the source.
In the case of woch, it was revealed in an article in the KLI's now-defunct journal HolQeD, volume 13 issue 4. I think it was printed in Spring 2004.
By the way, Klingon does not technically have adjectives. woch is a verb, and like all "be something" verbs, it can be used like an adjective by following a noun or noun phrase. This course uses the term adjective somewhat loosely and misleadingly.
The man is tall. (a sentence)
tall man (a noun phrase)