Definition
A substance formed when two or more chemical elements combine in fixed proportions, producing a new material whose properties differ from those of the original elements. The elements in a compound are joined chemically and cannot be separated by simple physical means.
Plain English
A new substance made when different elements join together chemically. Once they combine, they act as one material, not as the separate ingredients that went into it.
Context Anchor
Seen in aviation maintenance, aircraft materials, fuels, cleaners, sealants, and basic chemistry discussions.
Derivation
From the Latin componere, meaning 'to put together.' A compound is literally something put together from parts — but joined chemically, not just mixed.
Why Pilots Care
Pilots and mechanics need to know whether a material is approved for aircraft use. The wrong cleaning compound, sealing compound, or chemical compound can damage aircraft parts or create a safety problem.
Intuition Check
Do not read compound as simply “complicated.” In this context, compound means a material made from different basic substances joined together.
Example Sentence 1
Example Sentence 2
After sanding, apply a light polishing compound to restore the shine on the leading edges.