sidecar

noun

1. A one-wheeled attachment to the side of a motorcycle to allow for a separate seat for a passenger or cargo space.
2. A cocktail made with cognac (or brandy), triple sec liqueur, and lemon juice.

   “Faux 19th-century bartenders in sleeve garters and baroque facial hair ply their trade in pre-Prohibition bars. Women wearing cloche hats order sidecars at speakeasies.”

3. A software component that runs in a separate process from the rest of the software, to provide isolation and encapsulation.

   “Using generic sidecars for multiple microservices may introduce functionality overhead.”