Definitions

1. noun

A vehicle with two people riding or driving together, often a tandem bicycle or a motorcycle and sidecar, where one person is in the front and the other in the back.

“The couple rode their semitandem through the countryside.”

2. noun

A pair of people or animals that go together, especially for a particular task or journey.

“The semitandem of horses pulled the carriage through the city streets.”