corn mayweed n ubiquitous European annual weed with white flowers and finely divided leaves naturalized and sometimes cultivated in eastern North America; sometimes included in genus Matricaria n European white-flowered weed naturalized in North America Synonym(s) scentless camomile scentless false camomile scentless mayweed scentless hayweed Tripleurospermum inodorum Matricaria inodorum corn chamomile field chamomile Anthemis arvensis