We're all probably studying Japanese, right? So why doesn't anyone ever tell us the actual useful words for learners?? I'll start making a list here as I find them.

違い　a difference (ex. in word usage: 何 の 違い what kind of difference?). when i want to know the difference between two different kanji i just write something like "熱　暑　違い" into google and see what comes up.
語源　word origin = etymology
読み方　"read-method" = pronunciation
動詞　move word = verb
複数　more than one (layer) number = plural
形容(詞)　modify (word) = adjective
同義語　same duty word = synonym
辞書　word (compared to grammar) writings = normal dictionary
字書　letter writings = kanji dictionary (though i don't know if they have another term for it)
意味　meaning
さま (様)　means the same as 様子 which is "tends to behave like; form", in the case of words: "tends to be used like, tends to mean".
ニュアンス　nuance
外来　arriving from overseas = foreign/loanword. 外 is short for 外国 or 海外 and 来 for probably 出来.
略語　short(ened) word = abbreviation (ex. JD, JP)
熟語　a 2+kanji word where the individual kanji have almost exactly the same meaning (ex. 思想)
　
宿題　(at-)lodging (work-)theme = homework
試験　test-try(?) = exam
受[試]験　receive-try(?) = taking an exam
模試[験]　imitation test = mock exam
授業　receive-knowledge work(?) = class lesson
卒業　? = graduate
予習　pre-learn = study in advance
練習　? = practice exercise (ex. listening drill)
復習　? = review-study
自習　self-study (ex. study at home the material you learned in class)
習う　learns (under someone's instruction; not necessarily a school-teacher)
勉強　study (not necessarily with anyone's help)
締め切り　tie-up(?) run-out/cut-off = deadline