noun
plan; intention; what one has in mind
Refers to a personal, often unspoken plan or intention. Conveys a sense of having a scheme or design in one's mind, sometimes with a nuance of calculation.
彼は何か腹づもりがあるようだ。
He seems to have some plan in mind.
腹づもりを話してくれないか。
Won't you tell me what you're planning?
Compound of 腹 (はら, 'belly, mind') and 積もり (つもり, 'intention, plan'). The combination suggests a plan held in one's mind.