(a.) Growing old; decaying with the lapse of time.

abiding advanced advanced in life advanced in years age-long age-old along in years ancient antediluvian antique chronic constant continuing developed diuturnal doddering durable elderly enduring evergreen full-blown full-fledged full-grown fully developed getting on gray gray with age gray-haired gray-headed grey grown old hardy hoar hoary immutable in full bloom intransient inveterate lasting long-lasting long-lived long-standing long-term longeval longevous macrobiotic mature matured mellow mellowed of long duration of long standing old old as Methuselah olden patriarchal pensioned off perdurable perduring perennial permanent perpetual persistent persisting remaining retired ripe ripened seasoned sempervirent senectuous senescent senile senior stable staying steadfast superannuated tempered timeworn tottery tough unfading venerable vital white white with age white-bearded white-crowned white-haired wrinkled wrinkly years old