Definition
An electronic circuit in which all of the components -- transistors, diodes, resistors, and the conductive paths between them -- are formed within a single small piece of semiconductor material, usually silicon. The entire circuit is built as one inseparable unit rather than being assembled from individually manufactured parts.
Plain English
A complete electronic circuit built into one tiny chip of silicon, with all its parts and connections made together as a single piece instead of wired together from separate components.
Context Anchor
Seen in discussions of avionics, electronic engine controls, radios, navigation equipment, and aircraft electrical system components.
Derivation
Semiconductor refers to materials like silicon that conduct electricity only partially -- somewhere between a conductor (like copper) and an insulator (like rubber). Integrated comes from the Latin integrare, meaning to make whole. So an integrated circuit is one in which the parts are made whole together, as a single unit, rather than connected after the fact.
Why Pilots Care
Nearly every electronic system in a modern aircraft depends on these chips. Understanding that an entire avionics function lives on a single small piece of silicon helps explain why a single component failure can take out a whole system, and why avionics repair usually means replacing a unit rather than fixing it.
Analogy
Think of it like a whole room of electronic parts shrunk down and built into one tiny chip. You do not see each part separately, but the chip still performs the work of many parts together.
Intuition Check
Do not read circuit here as a visible loop of wire in the aircraft. In this term, the circuit is a tiny built-in electronic pathway and set of parts inside a chip.
Example Sentence 1
The transponder's signal-processing functions are handled by a semiconductor integrated circuit no larger than a fingernail.
Example Sentence 2
Aircraft radios use semiconductor integrated circuits to process incoming signals without adding extra weight.