A tandem is two things that work together at the same time.
Imagine you and your friend are riding bicycles side by side. You're not competing, but instead working as a team to pedal through the countryside. That's an example of tandem - two people doing something together in sync. But the word can also refer to another kind of pairing: like a bicycle with its rider, or a car and its driver. In these cases, the "tandem" is just another way of saying that one thing is connected to or attached to another.
A carriage pulled by two or more draught animals (generally draught horses) harnessed one behind the other, both providing the pulling power but only the animal in front able to steer.
Together; working as one.
Example: Their skillful tandem work made the project quick and successful.
One behind the other.
Example: The horses were harnessed tandem.
