tandem

A two-wheeled carriage drawn by horses harnessed one before the other.

A team of carriage horses harnessed in single file.

A tandem bicycle.

An arrangement of two or more persons or objects placed one behind or adjacent to the other.

Having two identical components arranged one behind or adjacent to the other.

In electricity, in series.

One behind the other; in single file: as, to drive tandem (that is, with two or more horses harnessed singly one before the other instead of abreast).

A pair of horses (sometimes more) harnessed one before the other.

A carriage drawn by two or more horses harnessed one before the other.

A bicycle or tricycle on which two can ride, one in front of the other.