Wiktionary
n. (context anatomy English) A septum in the nose, separating the left and right airways in the nose, dividing the two nostrils.
WordNet
n. a partition of bone and cartilage between the nasal cavities
Wikipedia
The nasal septum separates the left and right airways in the nose, dividing the two nostrils.
It is depressed by the depressor septi nasi muscle.
Usage examples of "nasal septum".
A two-prong oxygen feed was snugged against his nasal septum The sweet, cool flow was welcome.
A large gold ring pierced his nasal septum and hung over his upper lip.
Meehan took a long curved needle and skillfully passed a thread from behind the lower lip, up through the nasal septum and down again, so that when he tightened the thread and tied it off, the jaw was raised.
How would that yellow number 2 pencil look as an ornament, inserted through a pierced ear-lobe or nasal septum?