n 1  cap  :  a small genus of East Indian and Chinese trees (family Simaroubaceae) that are chiefly tropical with bitter bark, pinnate leaves, and terminal panicles of ill-scented greenish flowers and that include the tree of heaven (A. glandulosa) whose bark has been used as a tonic, purgative, and anthelmintic  2  :  a tree of the genus Ailanthus .
 
   
 
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