Source : Webster's Revised Unabridged Dictionary (1913)

Neckweed \Neck"weed`\, n. (Bot.)
   (a) An American annual weed ({veronica peregrina}), with
       small white flowers and a roundish pod.
   (b) The hemp; -- so called as furnishing ropes for hanging
       criminals. --Dr. prior.

Source : WordNet®

Veronica peregrina
     n : North American annual with small white flowers widely
         naturalized as a weed in South America and Europe [syn: {purslane
         speedwell}]