autumnal UK /ɔːˈtʌm.nəl/US /ɑˈtʌm.nəl/ adjective2 •Of or relating to autumn. •Past the middle of life; in the third stage."The magistrates are God-fearing gentlemen, but merciful over-much,--that is a truth," added a third autumnal matron. — 1850 formsmore autumnal · most autumnal