v.tr. & refl. (often foll. by on, upon) 1 tr. express pleasure at the happiness or good fortune or excellence of (a person) (congratulated them on their success). 2 refl. think oneself fortunate or clever. congratulant adj. & n. congratulator n. congratulatory adj.
[ L congratulari (as com-, gratulari show joy f. gratus pleasing) ]