Como o Charles Krause comentou as palavras originalmente do latin tem essa correspondência com o português e as palavras de origem germânica não.
age (n.) late 13c., "long but indefinite period in human history," from O.Fr. aage (11c., Mod.Fr. âge) "age; life, lifetime, lifespan; maturity," earlier edage, from V.L. *aetaticum (cf. Sp. edad, It. eta, Port. idade "age"), from L. aetatem(nom. aetas), "period of life, age, lifetime, years," from aevum "lifetime, eternity, age," from PIE base *aiw- "vital force, life, long life, eternity" (see eon). Meaning "time something has lived, particular length or stage of life" is from early 14c. Used especially for "old age" since early 14c. Expelled native eld. Age-group attested from 1904, originally a term in the science of demographics.