se·nec·ti·tude \sə̇ˈnektəˌtüd, -ə.ˌtyüd\noun (-s) Etymology: Medieval Latin senectitudin-, senectitudo, irregular from Latin senectus old age (from sen-, senic-, senex old, old man) + Latin -tudin-, -tudo -tude — more at senior : old age 1 < the mental changes of senescence and senectitude — Science >