1. [n]  something of sentimental value
2. [n]  a metal or plastic disk that can be used (as a substitute for coins) in slot machines
3. [n]  an individual instance of a type of symbol; "the word`error' contains three tokens of `r'"

1. \To"ken\, n. (Weaving)
   In a Jacquard loom, a colored signal to show the weaver which
   shuttle to use.
   

2. \To"ken\ (t[=o]"k'n), n. [OE. token, taken, AS. t[=a]cen;
   akin to OFries. t[=e]ken, OS. t[=e]kan, D. teeken, G.
   zeichen, OHG. Zeihhan, Icel. t[=a]kan, teiken, Sw. tecken,
   Dan. tegn, Goth. taikns sign, token, gateihan to tell, show,
   AS. te['o]n to accuse, G. zeihen, OHG. z[=i]han, G. zeigen to
   show, OHG. zeig[=o]n, Icel. tj[=a], L. dicere to say, Gr.
   deikny`nai to show, Skr. di[,c]. Cf. {Diction}, {Teach}.]
   1. Something intended or supposed to represent or indicate
      another thing or an event; a sign; a symbol; as, the
      rainbow is a token of God's covenant established with
      Noah.
   2. A memorial of friendship; something by which the
      friendship of another person is to be kept in mind; a
      memento; a souvenir.
            This is some token from a never friend. --Shak.
   3. Something given or shown as a symbol or guarantee of
      authority or right; a sign of authenticity, of power, good
      faith, etc.
            Say, by this token, I desire his company. --Shak.
   4. A piece of metal intended for currency, and issued by a
      private party, usually bearing the name of the issuer, and
      redeemable in lawful money. Also, a coin issued by
      government, esp. when its use as lawful money is limited
      and its intrinsic value is much below its nominal value.
   Note: It is now made unlawful for private persons to issue
         tokens.
   5. (Med.) A livid spot upon the body, indicating, or supposed
      to indicate, the approach of death. [Obs.]
            Like the fearful tokens of the plague, Are mere
            forerunners of their ends.            --Beau. & Fl.
   6. (Print.) Ten and a half quires, or, commonly, 250 sheets,
      of paper printed on both sides; also, in some cases, the
      same number of sheets printed on one side, or half the
      number printed on both sides.
   7. (Ch. of Scot.) A piece of metal given beforehand to each
      person in the congregation who is permitted to partake of
      the Lord's Supper.
   8. (Mining) A bit of leather having a peculiar mark
      designating a particular miner. Each hewer sends one of
      these with each corf or tub he has hewn.
   {Token money}, money which is lawfully current for more than
      its real value. See {Token}, n., 4.
   {Token sheet} (Print.), the last sheet of each token. --W.
      Savage.
   

3. \To"ken\, v. t. [imp. & p. p. {Tokened}; p. pr. & vb. n.
   {Tokening}.] [AS. t[=a]cnian, fr. t[=a]cen token. See
   {Token}, n.]
   To betoken. [Obs.] --Shak.
   

1. A basic, grammatically indivisible unit of a language such as a keyword, operator or identifier. Compare: lexeme.

2. (Or "pumpkin") An abstact concept passed between cooperating agents to ensure synchronised access to a shared resource. Such a token is never duplicated or destroyed (unless the resource is) and whoever has the token has exclusive access to the resource it controls. See for example token ring.

If several programmers are working on a program, one programmer will "have the token" at any time, meaning that only he can change the program whereas others can only read it. If someone else wants to modify it he must first obtain the token.