In a manner that is correct or appropriate. She ensured that the equipment was properly maintained to avoid any malfunctions.
In a way that is socially acceptable or suitable. He was dressed properly for the formal dinner, wearing a suit and tie.
Thoroughly or completely. Make sure the paint is properly mixed before you start applying it to the walls.
Strictly or exactly; in fact rather than merely in name or appearance. The platypus is not, properly, a reptile but a mammal.