I was surprised to see this as part of a clue on tonight's Jeopardy! about some movie from 2017. It is the first time I had heard the Adamantium word outside of our long time member here.

It is a made up metal alloy that orginated from the X-MEN comics. It's bonded to Wolverine's skeleton and was at one time the metal in Captain America's shield, before the metal was changed to the equally made up vibranium in the movies, because of a licensing rights issue.