(n): a deposit of personal property as security for a debt
(n): a person used by another to gain an end
(n): a person who contributes to the fulfillment of a need or furtherance of an effort or purpose
(n): (chess) the least powerful piece; moves only forward and captures only to the side; it can be promoted to a more powerful piece if it reaches the 8th rank
(n): any of 16 white and 16 black pieces used in playing the game of chess
(n): borrowing and leaving an article as security for repayment of the loan
(n): obtaining funds from a lender
(v): leave as a guarantee in return for money
(v): give over to another for care or safekeeping
The chess piece comes from the Anglo-Norman for "walker". This is because pawns are the foot soldiers of chess.