The Collaborative International Dictionary
Neckweed
Neckweed \Neck"weed`\, n. (Bot.)
An American annual weed ( veronica peregrina), with small white flowers and a roundish pod.
The hemp; -- so called as furnishing ropes for hanging criminals.
--Dr. Prior.
Wiktionary
neckweed
n. 1 An American annual weed ((taxlink Veronica peregrina species noshow=1)), with small white flowers and a roundish pod. 2 (context humorous archaic English) The hemp plant, which furnishes ropes for hanging criminals.