may·weed 
(māwēd′)
(māwēd′)n.
A widespread weed (Anthemis cotula) in the composite family, having rank-smelling, bipinnately divided leaves and white-rayed flower heads. Also called dog fennel, stinking chamomile.
[Middle English maythe weed, mayyen wed, alteration (influenced by May and maiden) of maithe, from Old English mægtha.]