good thing; nice thing
General expression for something positive, beneficial, or pleasant.
good excuse; good opportunity; taking advantage of
Used in the pattern 〜をいいことに(して) meaning 'taking advantage of (a situation)' or 'using as a good excuse'. Often carries a negative nuance of exploiting a situation.
Children's language or casual expression meaning 'That's a good idea' or 'Let's do that'. Often used as a suggestion.
Interjection used to impress an idea or urge a response, often by women or in casual speech. Similar to 'Hey, guess what?' or 'You know what?'.
Something good happened today.
Exercise is a good thing for your body.
He took advantage of being busy and skipped the meeting.
Taking advantage of his parents being away, he invited friends over and had a party.
I've got a good idea!
Going to the park is a good idea, isn't it?
Hey, why don't you come to the party tomorrow?
Listen, I'll tell you a secret.
こと is a nominalizer meaning 'thing' or 'matter'; combined with いい it forms the phrase いいこと.
Kanji spelling using 事; acceptable but less common than kana.
Rare kanji spelling emphasizing 'good' or 'likeable'.
Rare kanji spelling emphasizing 'morally good'.
Combination of the adjective いい (good) and the nominalizer こと (thing). The interjection and children's usage developed from the idea of presenting a 'good thing' or 'good idea'.