What does acerbity mean?
The definition of acerbity
A*cerb”i*ty, n.
Etym: [F. acerbité, L. acerbitas, fr. acerbus. See Acerb.]

1 Sourness of taste, with bitterness and astringency, like that of unripe fruit.
2 Harshness, bitterness, or severity; as, acerbity of temper, of language, of pain. Barrow.