1A native or inhabitant of Peoria, Illinois. Also allusively: a member of any American community in which plain, down-to-earth, conventional tastes and attitudes prevail.

2Geology. The Peorian deposits; the Peorian interglacial period.

Geology. Of, relating to, or designating extensive deposits, especially of loess, laid down during the final Pleistocene (Wisconsin) glaciation of North America. Also: designating an interglacial period between the Iowan and Wisconsin glaciations.