Congruent is the adjectival form of the noun congruence, and means in agreement with or matching. Mathematically, congruent means having the same size and shape, being identical in form. The antonyms are incongruent and incongruence.
Congruous means to be agreement or harmony, usually in an aesthetic sense. It is rarely used, while its antonym, incongruous, is more common.
Congruity is a noun referring to a harmonious or matching state. It is related to both congruence and congruous.
All of these words come from the root congruere, which means agree.
Examples
But there is the problem of integrating the diverse regulatory and market trading systems that would have to become congruent across all borders of Europe. (Forbes)
The two sets of interests may be congruent in some instances, but they are never identical, because no two nations’ interests are ever identical. (Chicago Tribune)
We are here to develop and build further on our ‘Make in India’ strategy, which is congruent with the Government’s ‘Make in India’ initiative.(The Hindu Business Line)
The line between genius and insanity is thin and sadly, Simone’s musical brilliance and manic depression were congruent. (Essence)
“The last four years there’s been an acceleration, and in a good way,” he said. “The stuff going up is very well thought-out and congruous to the neighborhood.” (Real Estate Weekly)
Unlike the other portraits, which appear to be congruous with a specific narrative, her self-portrait presents an optical illusion of the leopard-print shirt she is wearing against a leopard-print background. (Mail & Guardian)
Keeping the styling congruous, the granite extends the full height of the wall, adding swish to the backsplash. (Calgary Herald)