Entirely
Completely, Not At All
adverb
It's all nature out there. It's entirely nature and not at all city.
This word is weird. It means two opposite things. Thanks Japanese! Just look out for a negative word after the 全然. If it is negative it's "not at all" if it's not negative it might be "entirely."
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
全然ちがう
completely different
全然ない
to not have any of something
全然分からない
to not understand at all
ハリケーンとの天気予ほうがあったのに、全然雨がふらなかった。
Even though the weather forecast said there was a hurricane, we didn't get any rain at all.
「すみませんが、ちょっとたのみ事をしてもいいですか。」「はい、全然いいですよ！」
"Excuse me, but may I ask you for a small favor?" "Sure, of course!"
「分かりましたか？」 「申し訳ないのですが、チンプンカンプンで全然分かりません。今言ったことをもう少しゆっくり言っていただけませんか？」
"Did you get that?" "I’m sorry. I’m completely lost. Could you say that again more slowly?"