The Chinese word 性欲 (xìngyù), meaning "sexual desire" or "libido", is a compound formed through the combination of two distinct morphemes. The first character, 性 (xìng), means "nature", "character", or specifically in this context, "sex" or "gender", relating to the inherent qualities of a being. The second character, 欲 (yù), means "desire", "wish", or "longing". When combined in this modifier-head structure, 性 acts as the modifier specifying the type of desire, and 欲 acts as the head noun representing the core concept of "desire", thereby creating the precise meaning of "desire pertaining to sex". This follows a common pattern in Chinese where two characters with related meanings are joined to form a new, more specific abstract noun.