gluteus maximus

[mak-suh-muh s] /ˈmæk sə məs/
noun, plural glutei maximi
[mak-suh-mahy] /ˈmæk səˌmaɪ/ (Show IPA)
1.
the broad, thick, outermost muscle of the buttocks, involved in the rotation and extension of the thigh.
2.
Facetious. the buttocks.
Origin
1900-05; < Neo-Latin: largest gluteus