late 15c., from Old English fneosan "to snort, sneeze," from Proto-Germanic *fneusanan (cf. Middle Dutch fniesen, Dutch fniezen "to sneeze;" Old Norse fnysa "to snort;" Old Norse hnjosa, Swedish nysa "to sneeze;" Old High German niosan, German niesen "to sneeze"), from Proto-Germanic base *fneu-s- "sneeze," of imitative origin, as is PIE *pneu- "to breathe" (cf. Greek pnein "to breathe").
Other imitative words for it, perhaps in various ways related to each other, include Latin sternuere (cf. Italian starnutare, French éternuer, Spanish