The word **半天** is formed as a compound of two characters: **半** (*bàn*), meaning "half," and **天** (*tiān*), meaning "day" or "sky." Literally, it translates to "half a day," but its formation follows a common pattern in Chinese where a concrete time measurement is used to express a more abstract or figurative duration. In practice, it extends beyond the literal six or twelve hours to mean **a long while** or **quite some time**, often implying the speaker feels the duration was excessive or tedious. This semantic shift from a precise measure to an indefinite, emphatic period is what defines its common usage, such as in the phrase "我等了你半天" ("I waited for you for ages").