膨らむ

ふくらむ · fukuramu · JLPT N2 · verb-godan

to swell

🎈 ふく (blow air in) makes it swell: blow in air and it expands and swells out

膨 pairs the flesh radical 月 with 彭, a sound element. ふくらむ comes from ふく, to blow, so air blown in makes things swell and expand.