Agreeing or in harmony with something; appropriate or suitable in character or circumstance.
From Latin congruus, meaning 'coming together,' 'agreeing,' or 'fitting,' derived from congruere, a combination of con- (together) and a root related to 'to go' or 'to meet'.
Congruous is the word that makes you realize why a casual t-shirt feels wrong at a wedding—not because rules are arbitrary, but because context demands certain things fit together aesthetically and socially.
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