The word "伟绩" is formed by combining the character "伟", which means "great" or "grand", with the character "绩", which means "achievement" or "merit". In this compound, "伟" acts as a modifier that describes the nature of "绩", resulting in a word that literally means "great achievement". This construction directly links the descriptive quality of greatness to the concept of an accomplishment, forming a specific term for notable feats.