From tachah (or tuwach) in the sense of overlaying; (in the plural only) the kidneys (as being covered); hence (figuratively) the inmost thought -- inward parts.
see HEBREW tachah
see HEBREW tuwach
H2910. tuchah
טֻחוֺת noun feminine plural inward parts (as covered over, concealed) — טֻחוֺת of seat of faithfulness, בַּטּ חָפַצְתָּ ׳אֱמֶת Psalm 51:8 faithfulness thou desirest in the inward parts, i.e. in the heart ("" סָתֻם); of seat of wisdom בַּטּ שָׁת ׳מִי חָכְמָה Job 38:36 ("" שֶׂכְוִי q. v.); from context this can hardly = heart of man (kidneys, 'reins,' ᵑ7, Jewish interpretations, see NHWBii, 144 and others), but is rather cloud-layers (as dark, hidden spaces, see Di VB); their 'wisdom' appears in their obedience to natural law.
טיט טוט, (√ of following; meaning unknown).