Reins
A Biblical term that is often translated or used as heart or mind, that literally means “kidneys” (pl.) or “loins,” from the Hebrew kilyah, (כִּלְיָה)1 and the Greek ephros, (νεφρός) meaning “kidney,” fig. the (inmost) mind. The reins are the seat of the inward feelings, emotions, and passions of man.2
1 Strong’s Concordance, H3629.
2 Ibid., G3510.