asperity

From Old French asprete, from Latin asperitatem, from asper (“rough”).

• (Received Pronunciation) IPA^(key): /əˈspɛɹɪti/
• (General American) IPA^(key): /əˈspɛɹɪɾi/

asperity (countable and uncountable, plural asperities)

1. Roughness as of stone or weather.

   the asperity of Maine's winter

2. Harshness, as of temper.
   • 1878, W. S. Gilbert, H.M.S. Pinafore:

     Go, ribald, get you hence
     To your cabin with celerity.
     This is the consequence
     Of ill-advised asperity!

3. Something that is harsh and difficult to endure.
4. (geology) A part of a geological fault line that does not move.

   Earthquakes begin and end at asperities.