“Lucky break” is an idiom used to describe an unexpected stroke of good fortune, especially in a difficult situation. For example, imagine someone standing in a park when a tree suddenly falls. The trunk lands on either side of the person but misses them completely. In that moment, you could say, “That was a lucky break!” In a work or professional environment, consider someone who narrowly avoids a major mistake in a project because a last-minute change prevents the error from happening. A cowor