Definitions:
a part that is added to something to enlarge or prolong it

a length of electric cable which permits the use of appliances at some distance from a fixed socket.

a subsidiary telephone on the same line as the main one

the action of moving a limb from a bent to a straight position

denoting instruction by a university or college arranged for people who are not full-time students

the range of a term or concept as measured by the objects which it denotes or contains.

the property of occupying space