felicity: [14] Felicity and its relatives felicitous [18] and felicitate [17] all come ultimately from Latin fēlīx. This originally meant ‘fruitful’ (it is probably related to English fecund and foetus) but by classical times had progressed semantically via ‘favourable, fortunate’ to ‘happy’. => fecund, foetus[felicity etymology, felicity origin, 英语词源]