Origin of felwortMiddle English feldwort from Old English feldwyrt feld field ; see field . wyrt wort ; see wort 1.
Part or all of this entry has been imported from the 1913 edition of Webster's Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.
Probably a corruption of fieldwort.