concealing one's thoughts; reserve; holding back
Almost always used in negative constructions like 腹蔵なく (without reserve, frankly) or 腹蔵のない (open, unreserved). The word itself is somewhat formal and not used in casual speech.
See also: 腹蔵なく
Please give your opinion without holding back.
He has an open personality and is liked by everyone.
遠慮 means 'restraint' or 'hesitation' out of politeness. 腹蔵なく implies speaking without hiding anything, while 遠慮なく means 'without reserve' in the sense of not holding back out of politeness.
Standard kanji form. 腹 (belly) + 蔵 (store) suggests storing thoughts inside.
Variant kanji form using 覆 (cover/conceal). Less common than 腹蔵.
Compound of 腹 (belly, mind) and 蔵 (store, hide). The idea of storing thoughts in one's belly is a traditional metaphor for concealing one's true feelings. The exact historical derivation is uncertain.