FROM STRONG’S HEBREW DICTIONARY (1890)

Strong’s Hebrew Dictionary (1890) — public domain, printed whole.

tuwchah too-khaw' — from 2909 (or 2902) in the sense of overlaying; (in the plural only) the kidneys (as being covered); hence (figuratively) the inmost thought:--inward parts.

see HEBREW for 02909 see HEBREW for 02902