Source : Webster's Revised Unabridged Dictionary (1913)

Sneezewort \Sneeze"wort`\, n. (Bot.)
   A European herbaceous plant ({Achillea Ptarmica}) allied to
   the yarrow, having a strong, pungent smell.

Source : WordNet®

Achillea ptarmica
     n : Eurasian herb having loose heads of button-shaped white
         flowers and long gray-green leaves that cause sneezing
         when powdered [syn: {sneezeweed yarrow}, {sneezewort}]