The most common Korean word for “second day” is 이틀 (iteul). 「second day」는 한국어로 이틀.
Learn 이틀 free — flashcards, audio and review →「이틀」 단어장으로 무료로 외우기Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato