An adhesive is something sticky that holds things together. Use an adhesive to repair a cracked plate.
Adhesive comes from the Latin adhaerere, meaning "stick to," which is precisely what something adhesive does — it sticks to things. An adhesive bonds surfaces together. It's the sticky side on a roll of duct tape that causes it to be so effective. The word can be used to describe both the substance itself: to use an adhesive, for example — or its property of stickiness: an adhesive bandage sticks to the skin.