Entry 2 senses Webster, 1913 Thigh /(thī)/ · IPA /θaɪ/ 01 n. The proximal segment of the hind limb between the knee and the trunk. See Femur. 1. The proximal segment of the hind limb between the knee and the trunk. See Femur.(Anat.) See: Femur 2. The coxa, or femur, of an insect.(Zool.) Phrases & compounds Thigh bone — the femur.