What is the opposite of liner?

Opposite of liner depends on context because liner means inner layer or lining, so opposite would be outer layer, exterior, outside, or something that is not lining. In clothing context, liner is inner fabric, opposite is outer shell, outer fabric, or exterior. In container context, liner is inner protective bag, opposite is outer container, shell, or exterior. In shipping, ocean liner is ship, opposite not applicable but could be small boat. In general, liner as inner layer opposite is outer layer, covering, or shell. If liner means something that lines inside, opposite could be outer, external, or outside. In cosmetics, eyeliner lines eyes, opposite could be no liner or bare. In engineering, liner lines cylinder, opposite is block or housing that surrounds liner. So opposite of liner is outer layer, exterior, outer shell, or outside, representing external layer rather than internal lining, as liner is defined as inner layer, so opposite is outer layer that is outside rather than inside.