팽창이 · 팽창을
expansion, swelling; inflation (of currency)
Example
물은 얼면 부피가 약 10% 팽창합니다.
When water freezes, its volume expands by about 10%.
Word parts
팽 swell+창 expand
Literally 'swell and bloat'; both syllables mean getting bigger.
Good to know
Add 하다 for the verb: 공기가 팽창하다 'the air expands'; for prices, 인플레이션 or 물가 상승 is more common.