\Sec"un*dine\, n. [Cf. F. secondine.]
1. (Bot.) The second coat, or integument, of an ovule, lying
   within the primine.
Note: In the ripened seed the primine and secundine are
      usually united to form the testa, or outer seed coat.
      When they remain distinct the secundine becomes the
      mesosperm, as in the castor bean.
2. [Cf. F. secondines.] The afterbirth, or placenta and
   membranes; -- generally used in the plural.