全然 (zenzen), adverb
全然 (zenzen) is usually used in a negative sentence to emphasize the negative statement, and it means “not … at all”. For instance, “全然できなかった” means “couldn’t do at all”, and “全然食べなかった” means “didn’t eat at all”. Also, “全然ダメ” is a very common expression that means “completely useless/hopeless”, where ダメ (or 駄目) means “bad”, “useless”, or “hopeless”
There are some equivalent words to 全然 such as ‘全く (mattaku)’ and “一切 (issai)”, and these words are basically interchangeable. If you want to be sophisticated in writing, or to sound like a pedantic weirdo when talking with your Japanese friends, you may use “ゆめゆめ (yumeyume)”, as in “ゆめゆめ思わなかった” meaning “didn’t think in the least”.
Contrary to the general definition described in the last entry, 全然 (zenzen) is actually used in an affirmative sentence among young people. For instance, they say “全然眠い” (zenzen nemui) meaning “very sleepy”, and “全然美味しい” (zenzen oishii) meaning “really tasty”. In these expressions, 全然 works as an intensifier that emphasises the statement.
More importantly, it also contains a connotation that the situation you’ve experienced is unexpected; for example you would say “全然眠い” after you slept for like 9 hours, and “全然美味しい” when someone made a negative comment on the meal but you think it’s totally OK and rather tasty. In particular, “全然いいよ” (zenzen iiyo) and “全然OK” (zenzen OK) are very common phrases you use when someone apologizes to you but you think that’s totally fine. These phrases are so common that they don’t sound too casual compared to the other expressions.
Rationale Behind the Casual Usage
As you may have learnt in a Japanese class, 全然 is usually used in a negative sentence and means “not at all”. On the other hand, it is also used affirmatively when one experiences something unexpected; that is, his/her expectation has turned out to be “全然正しくない (not correct at all)”. Therefore, in that sense 全然 still has the nuance of the original meaning.
As you may have learnt in a Japanese class, using 全然 in an affirmative sentence is considered to be wrong. Therefore, if you use this word this way to elderly or didactic people, they would most likely correct your Japanese. That also means that you should avoid using 全然 with the informal meaning in a Japanese exam. In other cases, however, using 全然 affirmatively will boost up the casualness and naturalness of your Japanese.
Ex1 (General Usage)
Because last night I didn’t sleep at all, I’m so sleepy now.
As in this example, zenzen is often used as an exaggeration, and in this sentence, the speaker would have slept for like a few hours.
Ex2 (General Usage)
I still haven’t done my homework al all, so honestly this situation sucks.
Ex3 (Casual Usage)
Everyone said this comedian was boring, but I think he is 全然 (rather very) funny.
Ex4 (Casual Usage)
I’m 全然 (actually, totally) fine, so don’t worry.
Synonyms for the General Definition: 全く、一切、ゆめゆめ : “not … at all”, “not … in the least”
Synonyms for the Casual Definition: 別に(rather, actually), わりと (rather, fairly)
Related words and phrases: None