/yar"oh/ , n.
1. a composite plant, Achillea millefolium, of Eurasia, having fernlike leaves and flat-topped clusters of whitish flowers, naturalized in North America.
2. any of various other plants of the genus Achillea, some having yellow flowers.
[ bef. 900; ME yar ( o ) we, OE gearwe; c. G Garbe sheaf ]