Definition
To act unalterably means to do something in a way that cannot be changed, modified, or reversed. It suggests a finality and permanence. Think of a decision that's been made and cannot be undone, or a law that's set in stone. It is similar to acting irrevocably or immutably. It's different from acting tentatively or provisionally; it suggests a firm and fixed state. It is the opposite of behaving flexibly.