glu·te·us 
(gltē-əs, gl-tē-)
(gltē-əs, gl-tē-)n. pl. glu·te·i (gltē-ī′, gl-tēī′)
Any of the three large muscles of each buttock, especially the gluteus maximus, that extend, abduct, and rotate the thigh.
[New Latin glūteus, from Greek gloutos, buttock.]
glute·al adj.