The Collaborative International Dictionary of English v.0.48:
Bahai \Ba*hai"\ (b[.a]*h[imac]"), n.; pl. Bahais (-h[imac]z).
A member of the sect of the Babis consisting of the adherents
of Baha (Mirza Husain Ali, entitled "Baha 'u 'llah," or, "the
Splendor of God"), the elder half brother of Mirza Yahya of
Nur, who succeeded the Bab as the head of the Babists. Baha
in 1863 declared himself the supreme prophet of the sect, and
became its recognized head. There are upwards of 20,000
Bahais in the United States.
[Webster 1913 Suppl.]
WordNet (r) 3.0 (2006):
adj 1: of or relating to Bahaism
n 1: a teacher of or believer in Bahaism