as·per·i·ty 
(ă-spĕrĭ-tē)
(ă-spĕrĭ-tē)n. pl. as·per·i·ties
1.
a. Roughness or harshness, as of surface, sound, or climate: the asperity of northern winters.
b. Severity; rigor.
2. A slight projection from a surface; a point or bump.
3. Harshness of manner; ill temper or irritability.
[Middle English asperite, from Old French asprete, from Latin asperitās, from asper, rough.]