n 1 a  cap  :  a large genus of herbs of the family Compositae having opposite leaves and flower heads that are discoid or have bright yellow rays  b  :  a plant of the genus Arnica  2 a  :  the dried flower head of any of several herbs of the genus Arnica (esp. A. montana) used for stimulant and local irritant effect esp. in the form of a liniment for bruises, sprains, and swellings  b  :  a tincture made from arnica .
 
 
 
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