mississippian

prop. n. 1. A geological period extending from from 310 million to 345 million years ago; it was associated with an increase of land areas, the presence of primitive ammonites, and emergence of winged insects; called also Missippian period and Lower Carboniferous period.
Syn. -- Missippian period, Lower Carboniferous, Lower Carboniferous period. [ WordNet 1.5 ]

2. A resident of Mississippi. [ WordNet 1.5 ]