Douglas Harper's Etymology Dictionary
1950, literally "daughter of command;" a Jewish girl who has reached age 12, the age of religious majority. Extended to the ceremony held on occasion of this.
Wiktionary
n. 1 (context Judaism English) A Jewish coming of age ceremony for a girl. 2 (context Judaism English) Someone who has come of age. vb. (context transitive English) To initiate someone in a bat mitzvah ceremony
WordNet
n. (Judaism) an initiation ceremony marking the 12th birthday of a Jewish girl and signifying the beginning of religious responsibility [syn: bath mitzvah, bas mitzvah]
v. confirm in the bat mitzvah ceremony, of girls in the Jewish faith
Usage examples of "bat mitzvah".
And Ruth was right: She'd pulled in roughly twenty thousand dollars for her bat mitzvah.
January 17, 2002the shooting attack during a bat mitzvah celebration at a banquet hall in Hadera.
But on a cold day, in a drafty room, chilled cucumber soup is about as welcome as a swarm of wasps at a bat mitzvah.