X body, loins, shaft, side, thigh

Boyd’s Bible Dictionary:

Placing the hand under the thigh was a form of adjuration mentioned
(Gen. 24:2; 47:29), and supposedly prevalent in patriarchal times, but only taken by inferiors, as by servants or sons, and as significant of subjection and the purpose of obedience.

Concise Bible Dictionary:

The part of man that is used to prefigure the seat of strength. Descendants are represented as coming out of the loins of a man (Gen. 35:11; Heb. 7:10). The loins were girded up for action and activity. God said to Job, “Gird up now thy loins like a man” (Job 38:3). In the Christian’s conflict with wicked spirits in the heavenlies he is exhorted to have his loins girt about with truth (Eph. 6:14).

Strong’s Dictionary of Hebrew Words:

Transliteration:
yarek
Phonic:
yaw-rake’
Meaning:
from an unused root meaning to be soft; the thigh (from its fleshy softness); by euphem. the generative parts; figuratively, a shank, flank, side
KJV Usage:
X body, loins, shaft, side, thigh