ex- ‘out’ + pandere ‘to spread’

source: [顔を膨らませるプリン｜無料GIF画像検索 GIFMAGAZINE 2948292]

become or make larger or more extensive:

〈物･事が〉(大きさ･数･重要性の点で)ふくらむ, 膨張する(↔ contract); ｟かたく｠ 〈たたまれていたものが〉広がる

e.g. no object : their business expanded into other hotels and properties

(大きさ･数･重要性の点で)〈物･事〉をふくらませる, 膨張させる; ｟かたく｠ 〈たたんだもの〉を広げる

e.g. with object : baby birds cannot expand and contract their lungs.

no object Physics (of the universe) undergo a continuous change whereby, according to theory based on observed redshifts, all the galaxies recede from one another.

no object (expand on) give a fuller version or account of:

«…について» さらに詳しく述べる, 詳説する(enlarge) «on» , ｟よりかたく｠ «upon»

e.g. Anne expanded on the theory.

expandable | ikˈspandəb(ə)l | adjective

expander | ikˈspandər | noun

expansibility | ikˌspansəˈbilədē | noun

expansible | ikˈspansəb(ə)l | adjective

late Middle English: from Latin expandere ‘to spread out’, from ex- ‘out’ + pandere ‘to spread’.