Terminology

• Carbon Fiber Reinforced Plastic (CFRP): Term for a polymer-matrix composite that is reinforced with cloth, mat, strands or any form of carbon fiber.
• Chopped strand: Continuous roving that is chopped into short lengths for use in mats, spray up or molding compounds.
• Composite: Three-dimensional combination of at least two materials differing in form or composition, with a distinct interface separating the components. Composite materials are usually manmade and created to obtain properties that cannot be achieved by any of the components acting alone.
• Epoxy: A thermosetting polymer containing one or more epoxide or oxirane groups, curable by reaction with amines or alcohols; used as a resin matrix in reinforced plastic products and as the primary component in certain structural adhesives. Cured epoxy resin is highly resistant to chemicals and water and its performance properties are relatively unaffected by extreme temperatures.
• Prepreg: Fibrous reinforcement (sheet, tape, tow, fabric or mat) preimpregnated with resin and capable of storage for later use. For thermosetting matrices the resin is usually partially cured or otherwise brought to a controlled viscosity, called B-stage. Additives (e.g., catalysts, inhibitors and flame retardants) are used to obtain specific end-use properties and/or improve processing, storage and handling characteristics.
• Resin: A solid or pseudo-solid polymeric material, often of high molecular weight, which exhibits a tendency to flow when subjected to stress, usually has a softening or melting range, and usually fractures conchoidally. As composite matrices, resins bind together reinforcement fibers and work with them to produce specified performance properties.
• Roving: Large filament-count tow; a collection of continuous fiber filaments, either as untwisted strands or twisted yarn.
• Sizing: A chemical solution used to coat fiber filaments, facilitating operations such as weaving or braiding. Sizing protects the filament from water absorption and abrasion (to minimize fiber wear) and also can be used to bind together and stiffen warp yarns during weaving. Sizing is usually removed and replaced with finish before matrix application. Also called size.
• Thermoplastics: A class of plastics that can be repeatedly softened by heating and hardened by cooling through a temperature range characteristic of the plastic, and that in the softened state can be reshaped by means of molding or extrusion.
• Thermosets: A class of plastics that, when cured by thermal and/or chemical or other means, become substantially infusible and insoluble. Once cured, a thermoset cannot be returned to the uncured state.
• Toll processing: A contractual arrangement wherein an organization provides limited or batched production of a raw material or semi-finished good for a client based on a fee
• Tow: Continuous, ordered assembly of essentially parallel, collimated filaments, normally continuous filaments without twist. Same as strand but used when the reference is specific to carbon fiber.
• Unidirectional: General term denoting orientation of fibers in one direction.
• Yarn: A continuous, ordered assembly of essentially parallel, collimated filaments, usually with a twist.

 All definitions attributed to: http://www.compositesworld.com/glossary/