What does acetous mean?
The definition of acetous
A*ce”tous (#; 277), a.
Etym: [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.