Geriatric

google

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1920s: from Greek gēras ‘old age’ + iatros ‘doctor’, on the pattern of paediatric .

wiktionary

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From geriatrics; sychronically, from Ancient Greek γῆρας(gêras, “old age”) + -iatric.

etymonline

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geriatric (adj.)

1909, formed in English from Latinized forms of Greek gēras, gērōs "old age" (from PIE root *gere- (1) "to grow old") + iatrikos "of a physician," from iatros (see -iatric).