What is the meaning of the word "contract"?

Definitions:

a binding agreement between two or more persons that is enforceable by law noun
- The contract clearly states that you cannot work for a competitor.
a variety of the card game bridge in which the bidder receives points only for the number of tricks that have been bid noun
- I enjoy a game of contract every now and again.
an order to kill someone, usually for money noun
- The mob boss put out a contract on the snitch.
in bridge, the highest bid, which sets the number of tricks that the bidder must make noun
- The game was challenging with such a high contract.
to be stricken by or fall victim to an illness verb
- Many individuals contracted the plague in London in 1665.
to become smaller or draw together verb
- My pupils contracted because of the extreme brightness.
to make smaller verb
- The heat contracted the woollen garment.
to reduce in scope while retaining essential elements verb
- I contracted the document so only the bare bones were there.