asperity

asperity \as-PAIR-uh-tee\, noun:

1. Roughness of surface; unevenness.
2. Roughness or harshness of sound; a quality that grates upon the ear.
3. Roughness of manner; severity; harshness.

The separation wave probes all the rocks in its path, moving forward until it hits another asperity or fault bend, whereupon it abruptly stops.
-- Sandra Blakeslee, "Quake Theory Attacks Prevailing Wisdom OnHow Faults Slip and Slide", New York Times, April 14, 1992

Many years later, when I was sketching in Rome, a grim-looking Englishwoman came up to me and said with some asperity, "I see you are painting MY view."
-- Lord Berners, A Distant Prospect

She spoke with great authority, with an asperity that didn't allow for sentimental accountings or ideological projections.
-- Daphne Merkin, "A Passion for Order", New York Times, November 17, 1996

Asperity comes from Latin asperitas, from asper, "rough." It is related to exasperate, "to irritate in a high degree," from ex- (here used intensively) + asperatus, past participle of asperare, "to roughen," from asper.