Sneeze: 1. As a verb, to suddenly expel air through the nose and mouth by an involuntary contraction of the muscles of expiration. 2. As a noun, the act of sneezing.
Sneezing is commonly caused by irritation of the nasal passages, as from pollens, house dust, pepper, or other particles. The sound of the word "sneeze" suggests the act. See also: Achoo syndrome; Photic sneeze reflex.