Acetous \A*ce"tous\ (#; 277), a. [L. acetum vinegar, fr. acere to be sour.]

1. Having a sour taste; sour; acid. ``An acetous spirit.'' --Boyle. ``A liquid of an acetous kind.'' --Bp. Lowth.

2. Causing, or connected with, acetification; as, acetous fermentation.

Acetous acid, a name formerly given to vinegar

Source: Webster's Revised Unabridged Dictionary (1913)