When wounded soldiers were treated for battlefield injuries in the 1700s, it was a custom to give them something to bite on, to serve as a distraction and to help them keep their jaws clenched tightly shut during painful procedures. This didn’t stop the pain, but it did give the men something else to focus on and, with their jaws busy holding an object, they were unable to scream — at least, not very loudly. These men were often given a bullet to bite on for this purpose, which gave rise to the phrase “bite the bullet.”
“Bite the bullet” was originally used quite literally, and referred only to the actual act of biting a bullet. Many times operations were performed in the field or in rough hospitals without the benefit of any kind of anesthetic. The soldier was given a bullet to bite down on. In order to avoid swallowing the bullet, he needed to maintain focus on the bullet between his teeth, helping him to think about something besides the pain he was enduring.
By the late 1800s, the phrase began to be used as an idiom to signify doing something that needed to be done, no matter how unpleasant. The act does not need to be physically painful, but is generally something that causes discomfort in some way. It can refer to all kinds of things people must do, choices they must make or circumstances they must deal with.
People “bite the bullet” when they make tough decisions, such as choosing to pay the high cost of private school for their children in order to realize the benefits many years later, or they might “bite the bullet” when choosing to drive an old, clunky car in order to have money available for other purposes. Government representatives may feel that they are being forced to “bite the bullet” when they must make unpopular choices for reasons they deem necessary.
No matter what the specific situation may be, this phrase indicates that a hard choice is being made. It usually also indicates that the person making the choice feels that the decision is inevitable and must be dealt with whether he or she wants to do so or not. Just as the soldier of the 1700s had to “bite the bullet” and endure terrible pain that ultimately was for his own good, people today use the phrase to indicate that they, too, are faced with a painful, uncomfortable task or decision that must be faced.