The word **衰退** (shuāituì) is a compound formed by combining two characters with related meanings to express a nuanced concept of decline. The first character, **衰** (shuāi), carries the core meaning of "to weaken," "to decline," or "to wane," often referring to a loss of strength or vitality. The second character, **退** (tuì), means "to retreat," "to recede," or "to move backward." When combined, they create a binome where both elements reinforce the idea of a backward movement or diminution; thus, **衰退** specifically denotes a process of recession, downturn, or decay, commonly used in contexts like economic recession (**经济衰退**) or mental decline (**记忆力衰退**). This pattern of pairing synonyms or near-synonyms is a standard method of word formation in Chinese to specify and intensify an abstract idea.