臥薪嘗胆[gashinshoutan] going through thick and thin to attain one's objective
魂胆[kontan] soul
大胆[daitan] bold
胆汁[tanjuu] bile
胆石[tanseki] gallstones

胆のう[tannou] gall bladder
胆力[tanryoku] courage
度胆を抜く[dogimowonuku] to knock or scare (someone) out of his or her wits
落胆[rakutan] discouragement