1
general::
Behave bravely or stoically when facing pain or a difficult situation, as in If they want to cut the budget deficit, they are going to have to bite the bullet and find new sources of revenue. This phrase is of military origin, but the precise allusion is uncertain. Some say it referred to the treatment of a wounded soldier without anesthesia, so that he would be asked to bite on a lead bullet during treatment. Also, Francis Grose's Dictionary of the Vulgar Tongue (1796) holds that grenadiers being disciplined with the cat-o'-nine-tails would bite on a bullet to avoid crying out in pain.
American Heritage Idioms
2
general::
Phrase(s): bite the bullet
Sl. to accept something difficult and try to live with it. • You are just going to have to bite the bullet and make the best of it. • Jim bit the bullet and accepted what he knew had to be.
McGrawhill's American Idioms And Phrasal Verbs