pyriformis
/ˌpɪrɪˈfɔːmɪs/(also piriformis) Anatomy and Zoology
noun
A gluteal (buttock) muscle, which arises from the sacrum and the ischium or sacrotuberous ligament and inserts into the greater trochanter of the femur, serving in humans to rotate the thigh laterally.
Origin
Late 17th century. From post-classical Latin pyriformis pyriform.