The word **衰老 (shuāilǎo)**, meaning "to age and deteriorate" or "senescence," is a typical Chinese compound formed through the combination of two semantically similar characters to create a more precise and vivid meaning. The first character, **衰 (shuāi)**, means "to decline," "weaken," or "wane," often referring to a loss of strength or vitality. The second character, **老 (lǎo)**, means "old" or "aged." When paired, they create a coordinative compound where both elements contribute to the overarching concept: **衰** emphasizes the process of physical decline and weakening, while **老** specifies the context of advanced age, together encapsulating the biological process of growing old and frail. This formation exemplifies how Chinese compounds often synthesize related ideas to express a nuanced, composite concept.