森诺曼期是地质年代中上白垩纪最下的一阶。

在时间上它位于阿尔布期（下白垩纪）和土仑期之前。

森诺曼期的命名来源于法国城市勒芒的新拉丁语称呼：Cenomanum。

森诺曼期的标准化石是学名为Calycoceras naviculare、Acanthoceras rhotomagense和满德尔菊石（Mantelliceras）的菊石。

The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding age. Both age and stage bear the same name.