(1):

(n.) Disagreeing; incongruous; being at variance; clashing; opposing; not harmonious.

(2):

(n.) Dissonant; not in harmony or musical concord; harsh; jarring; as, discordant notes or sounds.

(3):

(n.) Said of strata which lack conformity in direction of bedding, either as in unconformability, or as caused by a fault.