What is Cork ?
Cork is (noun) 1. a piece of light wood from the bark of a tree, which closes wine bottles He pulled the cork out of the bottle. The little boat bobbed up and down on the surface of the water like a cork. 2. material made from the very light bark of a type of tree She placed little cork mats on the table to stop the wine glasses marking it.(verb) to put a cork into a bottle When they had drunk half the bottle, she corked it up to use the following day.
source: Easier English, Student Dictionary Upper Intermediate Level