To bind means to tie or fasten things together securely. When you bind a stack of papers with a rubber band, you're holding them in one tight bundle. Books are bound when their pages are sewn or glued together along one edge and attached to a cover. Pioneers traveling west would bind their belongings with rope to keep them from falling off their wagons.

Bind also means to be required or obligated to do something. When you make a promise, you're bound to keep it. A contract binds people to follow through on their agreements. If a referee makes a call in a game, players are bound by the rules to accept it. You might say “I'm bound by my word” when you've committed to doing something, even if it's become inconvenient.

The word carries a sense of strength and permanence: things that are bound together stay together. That's why we talk about the bonds that hold families together, or the binding nature of important promises. When something binds you, whether it's rope or responsibility, it isn't easily shaken loose.