Meaning

noun an enveloping or covering membrane or layer of body tissue

noun any of a variety of loose fitting cloaks extending to the hips or knees

originBorrowed from Middle French tunique, from Latin tunica, possibly from Semitic (compare Aramaic [script needed] (kittuna), Hebrew כותנת (kuttoneth, “coat”), English chiton); or from Etruscan. Existed in Old English as tunece; unknown if that term was lost and then reborrowed later. Doublet of tunica.

Etymology from Wiktionary, CC BY-SA 3.0