What is the meaning of token?

noun

• An individual instance of a type of symbol.
  • usage: "the word`error' contains three tokens of `r'"
  • synonyms: item
• Something serving as a sign of something else.
• A metal or plastic disk that can be redeemed or used in designated slot machines.
• Something of sentimental value.
  • synonyms: keepsake, souvenir, relic

adjective

• Insignificantly small; a matter of form only (`tokenish' is informal. )
  • usage: "the fee was nominal"; "a token gesture of resistance"; "a toknenish gesture"
  • synonyms: nominal, tokenish