Etymology: L, semi, half, pronus, leaning forward
lying on one's side, with the thigh on the upper side flexed against the abdomen and the arm on the lower side extended back. See also Sims' position.
semiprone(sem-e-pron') [? + pronus, prone]
In a position on left side and chest, with both thighs flexed on abdomen, the right higher than the left, and left arm back. Synonym: Sims' position