Compression ratio. The ratio of the volume of a cylinder with the piston at the bottom of its stroke to the volume of the cylinder with the piston at the top of its stroke.

Computer aided design (CAD). Using a computer in the design of a product.

Computer aided design drafting (CADD). Using a computer in the design and drafting process.

Computer aided engineering (CAE). Using a computer in the engineering of a product.

Computer aided manufacturing (CAM). Using a computer in the manufacturing of a product.

Computer graphics. Drawing with the use of a computer.

Conduction. The transfer of heat which requires physical contact between an object that has a large amount of heat energy and one that has a smaller amount of heat energy.

Conductor. A material that will carry electric current.

Convection. The process by which heat is transferred by movement of a heated fluid (gas or liquid).

Corrosion. The deterioration of metal by chemical or electrochemical attack.

Cosine (cos). A trigonometric function comparing two sides of a right triangle as follows: adjacent side Cos = hypotenuse

Coulomb. A measure of electrical output. One coulomb is 6.24 × 1018 electrons.

Countersink. A tool that cuts a cone-shaped depression around a hole in order to allow a rivet or screw to set flush with the surface of the material.

Current. The flow of electrical charge.

Dalton’s Law. States that a mixture of several gases which do not react chemically exerts a pressure equal to the sum of the pressures which the several gases would exert separately if each were allowed to occupy the entire space alone at the given temperature.

Datum. An imaginary vertical plane or line from which all measurements of arm are taken. The datum is established by the manufacturer. Once the datum has been selected, all moment arms and the location of CG range are measured from this point.

Debonding. Separation of the bond between the skin laminates and the core of a composite structure.

Decibels. The unit for measuring sound intensity. One decibel is the smallest change in sound intensity the human ear can detect.

Decimal system. The number system, also called the base-ten system, based on the number 10. Consisting of ten symbols, or digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9), the main principle is that 10 is considered as a new unit from which point counting starts again.