To Elaborate on nO-One\'s answer:
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\\Sneeze\\, v. i. [imp. & p. p. Sneezed; p. pr. & vb. n. Sneezing.] [OE. snesen; of uncertain origin; cf. D. snuse to sniff, E. neese, and AS. fne[\'o]san.]
[Middle English snesen, alteration of fnesen, from Old English fnosan. See pneu- in Indo-European Roots.]
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It\'s got an unkown origin, but is has to do with the origin of the word, back to it\'s roots, etc.