Brennan is a common surname in the United States. The crossword solutions for Brennan are Eileen (6 letters), Eileens (7 letters), and Souter (6 letters). Eileen is a female given name of Irish origin, derived from the Gaelic word 'aveline', meaning 'HAZELNUT'. Eileens is a variant spelling of the same name. Souter is a Scottish occupational surname derived from the Old English word 'sutere', meaning 'TAILOR'.