asperity

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.

The quality of being difficult or unpleasant to experience; (countable) a thing that is harsh and difficult to endure; a difficulty, a hardship.

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.

Of sound: gratingness, harshness.

Of taste: harshness or sharpness; acridity, tartness.

Of writing: a lack of elegance and refinement; inelegance, roughness.