A story of doubtful authenticity, although widely circulated as being true, is that the idiom “saved by the bell” originated with eighteenth-century coffins equipped with bells for people to ring if they found themselves buried alive.
But what is the true origin of the phrase?
Many sources confirm it is derived from the sport of boxing and was first documented in the early 20th century. As Grammarist explains, when a boxer is knocked to the ground, he must get back to his feet before the referee counts to ten or the victory will be awarded to his opponent. However, if the end-of-round bell sounds before the prone boxer is counted out, then he is allowed to continue fighting in the next round. When the bell rings before a boxer can be counted out, he is said to have been saved by the bell.