NOUN (1)

1. a gender that refers chiefly (but not exclusively) to males or to objects classified as male;


ADJECTIVE (3)

1. of grammatical gender;

2. associated with men and not with women;

3. (music or poetry) ending on an accented beat or syllable;
- Example: "a masculine cadence"
- Example: "the masculine rhyme of `annoy, enjoy'"

The Collaborative International Dictionary of English v.0.48:

masculine \mas"cu*line\ (m[a^]s"k[-u]*l[i^]n), a. [L.
   masculinus, fr. masculus male, manly, dim. of mas a male: cf.
   F. masculin. See Male masculine.]
   1. Of the male sex; not female.
      [1913 Webster]

            Thy masculine children, that is to say, thy sons.
                                                  --Chaucer.
      [1913 Webster]

   2. Having the qualities of a man; suitable to, or
      characteristic of, a man; virile; not feminine or
      effeminate; strong; robust.
      [1913 Webster]

            That lady, after her husband's death, held the reins
            with a masculine energy.              --Hallam.
      [1913 Webster]

   3. Belonging to males; appropriated to, or used by, males.
      [R.] "A masculine church." --Fuller.
      [1913 Webster]

   4. (Gram.) Having the inflections of, or construed with,
      words pertaining especially to male beings, as
      distinguished from feminine and neuter. See Gender.
      -- Mas"cu*line*ly, adv. -- Mas"cu*line*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

masculine
    adj 1: of grammatical gender [ant: feminine, neuter]
    2: associated with men and not with women [ant: feminine]
    3: (music or poetry) ending on an accented beat or syllable; "a
       masculine cadence"; "the masculine rhyme of `annoy, enjoy'"
    n 1: a gender that refers chiefly (but not exclusively) to males
         or to objects classified as male

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "masculine":
   andric, animate, bull, common gender, feminine, gender, gentleman,
   gentlemanlike, gentlemanly, he, him, his, hombre, homme, inanimate,
   male, male being, male person, man, manful, manlike, manly,
   mannish, neuter, uneffeminate