Tandem (noun)

1. A pair of people or things working together or in close succession.
2. A bicycle built for two people, one sitting behind the other.

Origin:

From the latin word "tandem" meaning "at last" or "finally". the word came into english in the late 17th century and originally meant "arranged one behind the other".

Examples:

1. The couple rode a tandem bike on their vacation.
2. They worked in tandem to finish the project on time.
3. The tandem bicycle was perfect for their sightseeing trip.
4. The tandem kayak was perfect for the river trip.
5. The two dancers performed a beautiful tango in tandem.