Anatomy A small cavity or depression, as in a bone.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "fossa" in a sentence
"And the presence of the glands in this location might explain another unusual aspect of metriorhynchid cranial anatomy, namely the strange elongate, groove-like antorbital fossae present in these animals (the antorbital fossa is an accessory opening present on the side of the skull in archosaurs)."
"Response to David: some books say that fossa is pronounced 'foosh', which would agree with your comment."
"Dorian - a "fossa" - looks to us like a cross between a dog, a cat, a bat and a gerbil - or maybe a bear."