n 1  cap  :  a large genus of widely distributed shrubs and one woody vine (family Saxifragaceae) with opposite leaves and corymbose clusters of usu. sterile white or tinted flowers  2  :  any plant of the genus Hydrangea  3  :  the dried rhizome and roots of the wild plant of the genus Hydrangea (H. arborescens) formerly used in pharmacy as a diuretic .
 
 
 
Similar sounding terms:  drain·age 
 
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