In legal, travel, and insurance contexts in 2026, "completely incidental" refers to something that happens by chance or is a minor, subordinate part of a larger activity or transaction. For example, if you are traveling for business but spend an hour visiting a museum, that sightseeing is "completely incidental" to the primary purpose of the trip. In legal terms regarding the use of a person's image, if someone happens to walk into the background of a professional photo shoot, their appearance is incidental and usually doesn't require a release. In the world of finance, an "incidental expense" is a small, secondary cost (like a $2 tip for a bellhop) that occurs as part of a larger service. The key factor is that the incidental element is not the main focus and does not change the fundamental nature or primary intent of the overall event or contract.