You and your best friend have a bond that allows you to trust each other with all your thoughts and secrets. A bond is a connection between two things.
Bond can refer to a physical or emotional restraint as in a prisoner who might tear off his bonds and escape to freedom. If you are arrested, your parents will have to pay a bond to get you released from jail. If you don't show up to court, they will lose that money. A certificate of debt issued by a government or corporation is also called a bond. When you cash in the bond on a set date, you get your money back plus interest. In its meaning of "connection," bond can be used as a verb. Have you ever met someone and felt an instant connection? You can say that you bonded.