The inward parts, kidneys, or innermost chambers of a person. Used metaphorically for the deep interior of human consciousness — the hidden places where true character and motivation reside. Related to the verb 'to plaster' or 'to coat,' suggesting layers that cover what is deepest within.
Tuchah points to the biblical understanding that God sees and cares about our innermost being. While humans judge by outward appearance, God examines the tuchah — the hidden interior. This aligns with Psalm 51:6: 'You desire truth in the inward parts.' The New Covenant promise is that God will write His law on these very inward parts (Jeremiah 31:33).