A nostril is one of the two small openings in your nose that help you breathe and smell.
You probably use the word "nostril" when talking about noses or breathing. For example, if someone has a cold and their nostrils are congested, it means they can't breathe properly through their nose because of all the mucus. You might also use this word when referring to facial features, like when you're describing someone's nose as having big, flared nostrils. In medicine, nostrils can be affected by certain conditions or injuries that need treatment, so doctors and nurses may also use this term in their work.
Either of the two orifices located on the nose (or on the beak of a bird); used as a passage for air and other gases to travel the nasal passages.
