Origin: Latin prefix post-
Posterior has 7 different meanings across 2 categories:
the fleshy part of the human body that you sit on
"he deserves a good kick in the butt"
"are you going to sit on your fanny and do nothing?"
a tooth situated at the back of the mouth
"The dentist told me I needed to fill my posterior tooth because there was a deep cavity near the gum line."
The hinder parts of the body.
"The surgeon had to carefully examine the posterior region before performing the delicate spinal surgery."
located at or near or behind a part or near the end of a structure
"The surgeon carefully examined the posterior portion of the knee before making an incision to repair the torn ligament."
Nearer the rear or hind end; nearer the caudal end of the body in quadrupeds or the dorsal end in bipeds.
"The surgeon carefully examined the posterior aspect of the patient's leg to ensure no nerve damage occurred during the procedure."
Relating to or denoting presentation of a fetus in which the rear or caudal end is nearest the cervix and emerges first at birth.
"The obstetrician noted that the baby was presenting posteriorly, meaning its head would emerge before the rest of the body during delivery."