This idiom means to face a difficult or unpleasant situation with courage and resolve, enduring it despite the pain or discomfort. It suggests steeling oneself to do something necessary but undesirable, often used in contexts of tough decisions or hardships.

The phrase likely originated in 19th-century military medicine, where soldiers were given a bullet to bite during surgery without anesthesia to stifle screams. An early use appears in Rudyard Kipling’s 1891 novel *The Light That Failed*: ‘Bite on the bullet, old man.’ Earlier, a 1796 *Grose’s Classical Dictionary of the Vulgar Tongue* mentions biting a cartridge, hinting at battlefield origins. By the 20th century, it was widely used metaphorically, especially in British and American English, to describe facing any ordeal.