ˈsōəs noun
( plural pso·ai -ōˌī ; or pso·ae -ōˌē)
Etymology: New Latin, from plural of psoa psoas, from Greek, muscle of the loins
: either of two internal muscles of the loin that together form the tenderloin of animals used as food of which the larger arises from the anterolateral surfaces of the lumbar vertebrae and passes beneath Poupart's ligament to insert with the iliacus into the lesser trochanter of the femur and of which the smaller muscle often absent arises from the last dorsal and first lumbar vertebrae and inserts into the brim of the pelvis — called also respectively psoas major or psoas magnus and psoas minor or psoas parvus