1620s, "to render happy" (obsolete); 1630s, "to reckon happy;" from Late Latin felicitatus, past participle of felicitare "to make happy," from Latin felicitas "fruitfulness, happiness," from felix "fruitful, fertile; lucky, happy" (see felicity). Meaning "congratulate, compliment upon a happy event" is from 1630s. Related: Felicitated; felicitating. Little-used alternative verb form felicify (1680s) yielded adjective felicific (1865).