The Collaborative International Dictionary of English v.0.48:

male fern \male fern\ n.
   A fern of North America and Europe (Dryopteris filix-mas)
   whose rhizomes and stalks yield an oleoresin used to expel
   tapeworms. It is a member of the woodfern genus.
   [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Male \Male\, a. [F. m[^a]le, OF. masle, mascle, fr. L. masculus
   male, masculine, dim. of mas a male; possibly akin to E. man.
   Cf. Masculine, Marry, v. t.]
   1. Of or pertaining to the sex that begets or procreates
      young, or (in a wider sense) to the sex that produces
      spermatozoa, by which the ova are fertilized; not female;
      as, male organs.
      [1913 Webster]

   2. (Bot.) Capable of producing fertilization, but not of
      bearing fruit; -- said of stamens and antheridia, and of
      the plants, or parts of plants, which bear them.
      [1913 Webster]

   3. Suitable to the male sex; characteristic or suggestive of
      a male; masculine; as, male courage.
      [1913 Webster]

   4. Consisting of males; as, a male choir.
      [1913 Webster]

   5. (Mech.) Adapted for entering another corresponding piece
      (the female piece) which is hollow and which it fits; as,
      a male gauge, for gauging the size or shape of a hole; a
      male screw, etc.
      [1913 Webster]

   Male fern (Bot.), a fern of the genus Aspidium (Aspidium
      Filixmas), used in medicine as an anthelmintic, esp.
      against the tapeworm. Aspidium marginale in America, and
      Aspidium athamanticum in South Africa, are used as good
      substitutes for the male fern in medical practice. See
      Female fern, under Female.

   Male rhyme, a rhyme in which only the last syllables agree,
      as laid, afraid, dismayed. See Female rhyme, under
      Female.

   Male screw (Mech.), a screw having threads upon its
      exterior which enter the grooves upon the inside of a
      corresponding nut or female screw.

   Male thread, the thread of a male screw.
      [1913 Webster]

WordNet (r) 3.0 (2006):

male fern
    n 1: fern of North America and Europe whose rhizomes and stalks
         yield an oleoresin used to expel tapeworms [syn: male
         fern, Dryopteris filix-mas]