1To laugh (to make a vocal sound indicating amusement).
友達の冗談にみんなが大きく笑った。
Everyone laughed heartily at the friend's joke.
その場の雰囲気が和んで、つい笑ってしまった。
The mood relaxed and I couldn't help laughing.
赤ちゃんの笑う声はとても可愛い。
A baby's laugh is very cute.
2To smile (to show a mild, often silent expression of amusement or pleasure).
彼女は恥ずかしそうに笑った。
She smiled shyly.
先生は生徒の答えににこりと笑った。
The teacher smiled at the student's answer.
窓の外を見て、彼は静かに笑った。
He looked out the window and smiled quietly.
3To sneer at or ridicule (to laugh scornfully at someone or something).
彼は相手の失敗を嗤ってはいけない。
You must not sneer at someone's failure.
部下のミスを上司が笑うような態度を取った。
The boss took an attitude that seemed to laugh at the subordinate's mistake.
4To be dumbfounded or flabbergasted to the point of laughing (to laugh as a consequence of astonishment or disbelief).
あまりの失敗続きに、みんな呆れて笑ってしまった。
There were so many failures that everyone was dumbfounded and laughed.
彼の見事な勘違いに、思わず笑ってしまった。
At his spectacular misunderstanding, I couldn't help laughing.