nostril

nos·tril   (nŏs'trəl)    n.  Either of the external openings of the nose; a naris. [Middle English nostrille, from Old English nosthyrl : nosu, nose; see nas- in Indo-European roots + thyrl, hole; see terə-2 in Indo-European roots.]

nostril 

Main Entry: nos·tril
Pronunciation: 'näs-tr&l
Function: noun
1 : either of the external nares; broadly : either of thenares with the adjoining passage on the same side of the nasal septum
2 : either fleshy lateral wall of the nose

nostril nos·tril (nŏs'trəl)
n.
A naris.