angle of repose

WordReference Random House Unabridged Dictionary of American English © 2025

an′gle of repose′, [Geol.]

1. Geology the maximum slope, measured in degrees from the horizontal, at which loose solid material will remain in place without sliding. Cf. angle of slide. 

• 1875–80

Collins Concise English Dictionary © HarperCollins Publishers::

angle of repose noun

1. the maximum angle to the horizontal at which rocks, soil, etc, will remain without sliding