congruent (adj.)

mid-15c., "suitableness or appropriateness of one thing to another," from Latin congruentia "agreement, harmony, congruity," from congruen-, present-participle stem of congruere "agree, correspond with," literally "to come together," from assimilated form of com "with, together" (see con-) + a lost verb *gruere, *ruere "fall, rush" (see congruent). Meaning "fact or condition of according or agreeing" is from 1530s. Related: Congruency.

"agreement between things, harmony," late 14c., congruite, from Old French congruité "relevance, appropriateness" or directly from Late Latin congruitatem (nominative congruens) "agreement," from congruus "suitable, agreeing," from congruere "to agree, correspond with," literally "to come together," from assimilated form of com "with, together" (see con-) + a lost verb *gruere, *ruere "fall, rush" (see congruent).

To their ful cups, "kinde thanks" was my returne, with Gentlemanlike protestations, as "Truely, sir, I dare not," "It stands not with the congruity of my health." Congruitie, said I! how came that strange language in my mouth? I thinke scarcely that it is any Christen worde, and yet it may be a good worde for ought I knowe, though I neuer made it, nor doe verye well understand it .... ["Kemp's Nine Daies Wonder," 1600]