密西西比世（英语：Mississippian）是地球历史中的一个地质时代，被国际地层委员会所承认，也是石炭纪前期。密西西比纪的年代大约位于359至318百万年前。就像其他许多地质年代学的年代一样，科学家可以利用岩床来辨识出密西西比纪，虽然准确的起始与终结时间仍未确定。密西西比纪是根据美国的密西西比河来命名的，因为密西西比纪的岩层广泛分布在这里。

北美洲的密西西比纪岩层包含许多海洋石灰岩，年代介于宾夕法尼亚纪与泥盆纪之前。

The Mississippian (also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earliest/lowermost of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. As with most other geochronologic units, the rock beds that define the Mississippian are well identified, but the exact start and end dates are uncertain by a few million years. The Mississippian is so named because rocks with this age are exposed in the Mississippi River valley.