The word 期限 (qīxiàn) is formed by combining two characters, each contributing a core idea to create a unified concept. The first character, 期 (qī), fundamentally means a designated or fixed point in time, such as a date, term, or period. The second character, 限 (xiàn), carries the meaning of a limit, boundary, or restriction. When joined, the compound visually and conceptually represents a temporal boundary, the fixed time limit by which something must be completed or is valid, thus forming the meaning "deadline" or "time limit".