Cost reduction is the process used by companies to reduce their costs and increase their profits.

A cost overrun, also known as a cost increase or budget overrun, involves unexpected incurred costs.

A cost estimate is the approximation of the cost of a program, project, or operation.

Cost breakdown analysis is a method of cost analysis, which itemizes the cost of a certain product or service into its various components, the so-called cost drivers.

Cosmic rays are high-energy protons and atomic nuclei that move through space at nearly the speed of light.

A corrosive substance is one that will damage or destroy other substances with which it comes into contact by means of a chemical reaction.

A corrosion inhibitor is a chemical compound that, when added to a liquid or gas, decreases the corrosion rate of a material, typically a metal or an alloy, that comes into contact with the fluid.

Corrosion engineering is an engineering specialty that applies scientific, technical, engineering skills, and knowledge of natural laws and physical resources to design and implement materials, structures, devices, systems, and procedures to manage corrosion.

Corrosion is a natural process that converts a refined metal into a more chemically stable form such as oxide, hydroxide, carbonate or sulfide.

A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor carrying a high voltage.

Corn ethanol is ethanol produced from corn biomass and is the main source of ethanol fuel in the United States.

Taking rock samples from a well by means of a special tool — a “core barrel”.

The core–mantle boundary (CMB) of Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core.

A core sample is a cylindrical section of (usually) a naturally-occurring substance.

A core catcher is a device provided to catch the molten core material (corium) of a nuclear reactor in case of a nuclear meltdown and prevent it from escaping the containment building.

Copper zinc tin sulfide (CZTS) is a quaternary semiconducting compound which has received increasing interest since the late 2000s for applications in thin film solar cells.

A cooling tower is a heat exchanger in which air and water are brought into direct contact with each other in order to reduce the water's temperature

In the study of heat transfer, fins are surfaces that extend from an object to increase the rate of heat transfer to or from the environment by increasing convection.

Cooling degree day is a measurement designed to quantify the demand for air conditioning needed to cool a building.

Cooling is removal of heat, usually resulting in a lower temperature and/or phase change.