noun, noun which may take the genitive case particle 'no', adverb
full stomach; bellyful; eating heartily
Describes the state of being physically full after eating, or the act of eating until full. Often used adverbially with 食べる.
お腹いっぱいで、もう何も食べられない。
I'm so full I can't eat another bite.
今日はお腹いっぱい食べた。
I ate my fill today.
adverb
Used adverbially to mean doing something as much as one wants, not limited to eating. Often with verbs like 遊ぶ, 泣く, 話す.
休みの日はお腹いっぱい遊んだ。
On my day off, I played to my heart's content.
彼女はお腹いっぱい泣いた。
She cried her heart out.
Compound of お腹 (stomach, with honorific prefix) and 一杯 (full). The extended adverbial sense 'to one's heart's content' developed from the idea of filling the stomach to satisfaction.