ger ‧ on ‧ tol ‧ o ‧ gy /ˌdʒerɒnˈtɒlədʒi $ ˌdʒerənˈtɑː-/ BrE AmE noun [uncountable]
[ Date: 1900-2000 ; Language: Greek ; Origin: geron 'old man' + English -ology ]
the scientific study of old age and its effects on the body ⇨ geriatrics
—gerontologist noun [countable]
—gerontological /dʒəˌrɒntəˈlɒdʒɪk ə l◂ $ -ˌrɑːntəˈlɑː-/ adjective