Source : Webster's Revised Unabridged Dictionary (1913)

Mate \Mate\, n. [Perhaps for older make a companion; cf. also
   OD. maet companion, mate, D. maat. Cf. {Make} a companion,
   {Match} a mate.]
   1. One who customarily associates with another; a companion;
      an associate; any object which is associated or combined
      with a similar object.

   2. Hence, specifically, a husband or wife; and among the
      lower animals, one of a pair associated for propagation
      and the care of their young.

   3. A suitable companion; a match; an equal.

            Ye knew me once no mate For you; there sitting where
            you durst not soar.                   --Milton.

   4. (Naut.) An officer in a merchant vessel ranking next below
      the captain. If there are more than one bearing the title,
      they are called, respectively, first mate, second mate,
      third mate, etc. In the navy, a subordinate officer or
      assistant; as, master's mate; surgeon's mate.

Mate \Ma"te\, n. [Sp.]
   The Paraguay tea, being the dried leaf of the Brazilian holly
   ({Ilex Paraguensis}). The infusion has a pleasant odor, with
   an agreeable bitter taste, and is much used for tea in South
   America.

Mate \Mate\, n. [F. mat, abbrev. fr. ['e]chec et mat. See
   {Checkmate}.] (Chess)
   Same as {Checkmate}.

Mate \Mate\, a.
   See 2d {Mat}. [Obs.] --Chaucer.

Mate \Mate\, v. t. [F. mater to fatigue, enfeeble, humiliate,
   checkmate. See {Mate} checkmate.]
   1. To confuse; to confound. [Obs.] --Shak.

   2. To checkmate.

Mate \Mate\, v. t. [imp. & p. p. {Mated}; p. pr. & vb. n.
   {Mating}.]
   1. To match; to marry.

            If she be mated with an equal husband. --Shak.

   2. To match one's self against; to oppose as equal; to
      compete with.

            There is no passion in the mind of man so weak but
            it mates and masters the fear of death. --Bacon.

            I, . . . in the way of loyalty and truth, . . . Dare
            mate a sounder man than Surrey can be. --Shak.

Mate \Mate\, v. i.
   To be or become a mate or mates, especially in sexual
   companionship; as, some birds mate for life; this bird will
   not mate with that one.

Source : WordNet®

mate
     n 1: the officer below the master on a commercial ship [syn: {first
          mate}]
     2: a fellow member of a team; "it was his first start against
        his former teammates" [syn: {teammate}]
     3: the partner of an animal (especially a sexual partner); "he
        loved the mare and all her mates"; "camels hate leaving
        their mates"
     4: a person's partner in marriage [syn: {spouse}, {partner}, {married
        person}, {better half}]
     5: an exact duplicate; "when a match is found an entry is made
        in the notebook" [syn: {match}]
     6: South American holly; leaves used in making a drink like tea
        [syn: {Paraguay tea}, {Ilex paraguariensis}]
     7: informal term for a friend of the same sex
     8: South American tea-like drink made from leaves of a South
        American holly called mate
     9: a chess move constituting an inescapable and indefensible
        attack on the opponent's king [syn: {checkmate}]

mate
     v 1: make love; "Birds mate in the Spring" [syn: {copulate}, {pair},
           {couple}]
     2: bring two objects, ideas, or people together; "This fact is
        coupled to the other one"; "Matchmaker, can you match my
        daughter with a nice young man?"; "The student was paired
        with a partner for collaboration on the project" [syn: {match},
         {couple}, {pair}, {twin}]
     3: place an opponent's king under an attack from which it
        cannot escape and thus ending the game; "Kasparov
        checkmated his opponent after only a few moves" [syn: {checkmate}]