시간 (時間) is a Sino-Korean compound: 時 (시, *si*) meaning "time / hour" and 間 (간, *gan*) meaning "interval / between." The same Chinese characters appear in Japanese 時間 (*jikan*) and Mandarin 时间 (*shíjiān*), reflecting the shared Classical Chinese literary heritage across East Asia.

Koreans use 시간 in two slightly different ways that trip up learners: it means both "time" in the abstract (시간이 없다 – "I have no time") and a countable hour (세 시간 – "three hours"). For the clock reading itself ("It is 3 o'clock"), Koreans switch to 시 alone (세 시). Also note that punctuality is highly valued in Korean professional culture, so phrases built around 시간 — 시간을 지키다 ("to keep time / be punctual") — carry real social weight.