Unconditional order or promise to pay an amount of money, easily transferable from one person to another. Examples: check, promissory note, draft (bill or exchange). The Uniform Commercial Code requires that for an instrument to be negotiable it must by signed by the maker or drawer, must contain an unconditional promise or order to pay a specific amount of money, must be payable on demand or at a specified future time, and must be payable to order or to the bearer.

cf... Everything Dictionary of Finance and Investment Terms