老衰
ろうすい · rousui · JLPT N1 · noun
dotage
🥀 老 (old) + 衰 (decline): senility is the decline that comes with old age
Both kanji use Sino-Japanese readings: 老 (ろう, rō, old) and 衰 (すい, sui, decline). Together they name the gradual weakening that comes with old age.
老 — old man 耂 + 匕 (bent figure)
Originally a pictograph of an elderly person with long hair leaning on a cane. The top 耂 depicts the hair and stooped body, while 匕 at the bottom represents the cane or a bent figure. The core meaning 'old' has remained stable since oracle bone script.