The word 延长 is formed by combining two individual characters, each contributing its core meaning to create a new, composite concept. The first character, 延 (yán), carries the inherent idea of "to extend" or "to prolong". It is paired with the second character, 长 (cháng), which means "long". When placed together, their meanings fuse in a direct, logical manner: the action of 延 acts upon the state of 长, resulting in the combined meaning of "to lengthen" or "to prolong". It is a conceptual compound where the whole is a clear sum of its semantic parts.