This is actually a word in Korean. It is based on the English word but is now an accepted and incredibly common word in Korean. When that happens, the loan word is often changed, either in form (apartment to 아파트) or meaning (the whole idea of skinship, the words are English, the meaning is not). This can be confusing to native English speakers and you just have to learn their meanings.
아파트 is actually the official Korean word for apartment. Its written on the side of almost every apartment building and everyone knows it in this form. Loan words often get changed in either meaning or form when they are adopted into Korean and it can be a little odd. But this is correct.