baptism (n.)youdaoicibaDictYouDict[baptism 词源字典]
c. 1300, bapteme, from Old French batesme, bapteme (11c., Modern French baptême), from Latin baptismus, from Greek baptismos, noun of action from baptizein (see baptize). The -s- restored in later 14c.

Figurative sense is from late 14c. The Anglo-Saxons used fulluht in this sense (John the Baptist was Iohannes se Fulluhtere). Phrase baptism of fire "a soldier's first experience of battle" (1857) translates French baptême de feu; the phrase originally was ecclesiastical Greek baptisma pyros and meant "the grace of the Holy Spirit as imparted through baptism." Later it was used of martyrdom, especially by burning.[baptism etymology, baptism origin, 英语词源]