(1):

(v. t.) To redouble; to multiply; to repeat.

(2):

(v. t.) To repeat the first letter or letters of (a word). See Reduplication, 3.

(3):

(a.) Double; doubled; reduplicative; repeated.

(4):

(a.) Valvate with the margins curved outwardly; - said of the /stivation of certain flowers.