The Collaborative International Dictionary of English v.0.48:

Boza \Bo"za\, n. [See Bosa.]
   An acidulated fermented drink of the Arabs and Egyptians,
   made from millet seed and various astringent substances;
   also, an intoxicating beverage made from hemp seed, darnel
   meal, and water. [Written also bosa, bozah, bouza.]
   [1913 Webster]