in the heart; in one's mind
Rare literary noun meaning the inner thoughts or feelings, something kept inside one's heart. Not used in everyday conversation; found in classical or poetic contexts.
He never revealed to anyone the feelings he kept in his heart.
The kanji 肚 means 'belly' or 'stomach' and 裏 means 'inside' or 'reverse', so the compound literally suggests 'inside the belly', metaphorically the seat of emotions. The exact historical derivation is uncertain; the word is a rare literary coinage.