I. pō-ˈstir-ē-ər, pä- adjective
Etymology: Latin, comparative of posterus coming after, from post after — more at post-
Date: 1534
1. : later in time : subsequent
2. : situated behind: as
a. : caudal
b. of the human body or its parts : dorsal
3. of a plant part : adaxial , superior
• pos·te·ri·or·ly adverb
II. pä-ˈstir-ē-ər, pō- noun
Date: circa 1616
: the hinder parts of the body ; specifically : buttocks