The word **不时** (bùshí) is a compound adverb formed by combining the negation **不** (bù, meaning "not") with the noun **时** (shí, meaning "time" or "moment"). Literally, it means "not at a fixed time" or "not by the clock." This literal sense evolved into its modern, figurative meaning of "frequently," "often," or "from time to time," describing actions or events that occur repeatedly but at irregular or unspecified intervals, rather than on a set schedule. Thus, its formation follows a common pattern in Chinese where a negative modifier combined with a concrete noun creates an abstract adverbial concept.