The Japanese word for to laugh is
笑う

わらう - warau

to laugh

Japanese Definition

笑う
1. v. to spontaneously express joy or amusement by means of the voice or facial expression:
2. v. to laugh
3. v. to smile
マイクがよく笑いますよね。 - Mike laughs / smiles a lot, doesn't he.
4. v. to split open (as a plant bud), to bloom
桜の花が笑う - the cherry flowers bloom
5. v. to split open from ripening (as fruit or vegetables)
栗が笑っている時期 - the season when the chestnuts ripen and split open
6. v. (metaphor) to bud, become green and verdant, and bloom in spring (as the landscape)
山の景色が笑う - the mountain landscape comes alive / quickens / blooms
7. v. to come undone (as a stitch or seam)
縫い目が笑っている - the seam is coming open
8. v. (slang) to become weak and wobbly (as in the knees)
膝が笑う - go wobbly in the knees
9. v. to laugh at, to make fun of, to make a fool of
ジュディは私を笑った。 - Judy laughed at me / made fun of me / made a fool of me.