(1):

(v. i.) Union of musical sounds which strikes the ear harshly or disagreeably, owing to the incommensurability of the vibrations which they produce; want of musical concord or harmony; a chord demanding resolution into a concord.

(2):

(n.) To disagree; to be discordant; to jar; to clash; not to suit.

(3):

(v. i.) Want of concord or agreement; absence of unity or harmony in sentiment or action; variance leading to contention and strife; disagreement; - applied to persons or to things, and to thoughts, feelings, or purposes.