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).

"rule by old men," 1830, a Latinized compound of Greek stem of geron (genitive gerontos) "old man" (from PIE root *gere- (1) "to grow old") + kratia "rule" (see -cracy). Related: Gerontocratic.

1903, coined in English from geronto-, used as combining form of Greek geron (genitive gerontos) "old man," from PIE root *gere- (1) "to grow old."