A choice made, closing the others. A decision is only real once something becomes impossible.
Latin decisio (a cutting off, decision), from decidere (to cut off, decide), from de- (off) + caedere (to cut); a choice made by cutting the other options away, real only once something has become impossible.
A choice made, closing off the others. It is only real the moment something else becomes genuinely impossible, not merely less preferred.