n. 1
The quality of having a rough or uneven surface; roughness, unevenness; (countable, chiefly in the plural) a protruding or rough area or point on a surface; a protrusion.
n. 2
The quality of being difficult or unpleasant to experience; (countable) a thing that is harsh and difficult to endure; a difficulty, a hardship.
the asperity of Maine’s winter
n. 3
The quality of being harsh or severe in the way one behaves or speaks toward another person; (countable, chiefly in the plural) a deeply hostile or resentful feeling; an animosity, a hatred.
n. 4
The quality of having a rough or uneven surface; roughness, unevenness; (countable, chiefly in the plural) a protruding or rough area or point on a surface; a protrusion. A section of a fault line with high friction, such that there is no movement along this part of the fault except during an earthquake.

Related words

Forms

Asperity or Acrimony?

One might speak with momentary asperity to his child, but not with acrimony, unless estrangement had begun.

J. C. Fernald, English Synonyms and Antonyms (1914)

Use in printed books, per decade from 1850 to 2019.

4 letters: bump¹
5 letters: rigor²
6 letters: rigour
8 letters: severity⁴, hardship², hardness², acrimony⁴, keenness, sourness, tartness², grimness², acerbity, acridity
9 letters: sharpness², roughness², harshness², virulence³, bumpiness
10 letters: bitterness³, ruggedness, unevenness, severeness, inclemency, causticity
12 letters: protuberance⁴, rigorousness
13 letters: corrosiveness, rigourousness

The small number after each word is its number of syllables (rigor² = 2 syllables).