1.nounA negating expression; an answer that shows disagreement or disapproval
2.nounA vote not in favor, or opposing a proposition
"The workers voted on whether to strike, and there were thirty "yeses" and two "nos"."
3.adverb(now only used with different, with comparatives more and less, and informally with certain other adjectives such as good and fun) Not, not at all.
"I just want to find out whether she's coming or no. (Scotland)"