Cost may mean:

• The amount of money needed to buy something
• Something other than money that is used up. Example: "Going to jail cost 5 years of my life". This usage is a metaphor.
• Cost function
• Cost of living, the amount of money it costs just to live in a certain place. It includes food, housing, etc.
• Opportunity cost, the value of the next best thing you give up whenever you make a decision.