Brown Driver Briggs

 Mordecai = "little man" or "worshipper of Mars"
1. cousin and adoptive father of queen Esther; son of Jair of the
tribe of Benjamin; deliverer under Divine providence of the
children of Israel from the destruction plotted by Haman the chief
minister of Ahasuerus; institutor of the feast of Purim
2. a Jew who returned from exile with Zerubbabel