Opposite of yes. Disagree, turn down, tell
someone they will not do
something,
don't want to, etc.
Also, it indicates possesive speech in Japanese.
1)
Mom: Jimmy, will you do the
laundry?
Jimmy: NO!
Mom: *kills Jimmy*
2)
Sensei no misete kudasai to kiite kudasai.
(Please watch and please listen to
teacher.)