posterior

Short definition from Wiktionary

Adjective

1. 1
   Nearer the rear or hind end; nearer the caudal end of the body in quadrupeds or the dorsal end in bipeds: Relating to or denoting presentation of a fetus in which the rear or caudal end is nearest the cervix and emerges first at birth.
2. 2
   Nearer the rear or hind end; nearer the caudal end of the body in quadrupeds or the dorsal end in bipeds: Next to, or facing the main stem or axis.
3. 3
   Following in order or in time.

Noun

1. 1
   The posterior portions of the human body; especially, the buttocks.
2. 2
   The probability that a hypothesis is true (calculated by Bayes' theorem).