The word **挚友 (zhìyǒu)**, meaning "close friend" or "bosom friend," is a compound noun formed through a common Chinese morphological process where two meaningful characters (morphemes) are combined. The first character, **挚 (zhì)**, carries the core meaning of "sincere," "earnest," or "deeply heartfelt," often implying a passionate and genuine commitment. The second character, **友 (yǒu)**, simply means "friend." Therefore, the compound **挚友** is formed in a **modifier-head structure**, where "挚" modifies the type of "友," effectively specifying a friend characterized by profound sincerity and deep emotional bond, resulting in the integrated meaning of an "intimate and devoted friend."