1Good; nice; pleasant — used to describe quality, condition, appearance, or character. The colloquial form of 良い (よい); in everyday speech, いい is far more common than よい.
今日はいい天気だね。
The weather's nice today, isn't it?
彼女はとてもいい人だよ。
She's a really nice person.
もっといい方法はないかな。
Isn't there a better way?
この映画、評判がいいらしいよ。
I hear this movie has a good reputation.
頭がいい子だね。
What a smart kid.
2Enough; sufficient; that'll do — indicating that something is adequate or that no more is needed. Commonly appears in phrases like もういい (that's enough) or これでいい (this is fine).
もういいよ、自分でやるから。
That's enough — I'll do it myself.
コーヒー、もう一杯いかが？ いえ、もういいです。
Another cup of coffee? — No, I'm good, thanks.
これでいいですか？
Is this all right?
準備はいい？ うん、いいよ。
Are you ready? — Yeah, I'm ready.
3Profitable; favorable; a good deal — used for advantageous conditions such as a high salary, generous terms, or a bargain price.
彼はいい仕事に就いた。
He landed a good job.
セールでいい買い物ができた。
I got a great deal at the sale.
それはなかなかいい話だね。
That sounds like a pretty sweet deal.
4OK; all right; you may — used in patterns like 〜てもいい (you may / it's OK to) or 〜といい (it'd be good if) to express permission, acceptance, or a light suggestion.
ここに座ってもいいですか？
May I sit here?
写真を撮ってもいいよ。
You can take pictures.
明日は来なくてもいいですよ。
You don't have to come tomorrow.
早く春が来るといいなあ。
I hope spring comes soon.