sidecar

noun3

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. — 2011
3. •
   A software component that runs in a separate process from the rest of the software, to provide isolation and encapsulation.