- congruent (adj.)
- early 15c., "suitable, proper," from Latin congruentem (nominative congruens) "agreeing, fit, suitable," present participle of congruere, literally "to come together, agree, correspond with," from com- "with" (see com-) + a lost verb *gruere, *ruere "fall, rush," perhaps from PIE *ghrei- "to rub, grind" (see chrism). Geometry sense attested by 1706.
