Volume. The amount of space within a three-dimensional solid.

Waterline (WL). A horizontal reference plane used to locate vertical positions on an aircraft. Positions are usually given in inches above or below the waterline.

Watt. A unit of power equal to one joule per second.

Weighing points. Locations on an aircraft that the manufacturer designates for the placement of scales when weighing aircraft.

Weight. A measure of the pull of gravity acting on the mass of an object.

Whole numbers. The numbers: 0, 1, 2, 3, 4, 5, and so on.

Wiring diagrams. A diagram that shows the electrical wiring and circuitry, coded for identification, of all the electrical appliances and devices used on aircraft.

Work. The amount of energy transferred by a force.

Zero fuel weight. The weight of an aircraft without fuel.

Zone numbers. On drawings, these are similar to the numbers and letters printed on the borders of a map, used for locating a particular point in the drawing.