I guess you mean a bolt-in swap. There are a few possible definitions, depending on who you ask.

1) Direct engine swap, as in pull out one engine and the other engine drops in with original stock parts. Example: putting a B20Z into a '98 Integra.
2) Swap using a combo of stock parts from multiple cars, possibly with a few wiring changes. Example: B18C into a '92 Civic.
3) Swap using a combo of mass-produced swap kits and stock parts from multiple cars. Example: B16A into an '89 CRX.

The general simple definition is any swap that doesn't take serious custom work to install.