(Latin: at length; in the sense of "lengthwise, one behind the other")

in tandem
If two things happen, or are used in tandem, they happen or are used at the same time; and if two people do something in tandem, they do it together.
1. A two-seated carriage drawn by horses harnessed one before the other; a team so harnessed.
2. A group of two or more arranged one behind the other or used or acting in conjunction; that is, in tandem.
3. A tandem arrangement; for example, in partnership or conjunction.
4. In aviation, a reference to controls, wings, landing gears, and such, having two or more like elements or units arranged one behind the other; also used to form compounds; such as "tandem boosters" and "tandem-powered".
5. In electricity, describing, or relating, to two-terminal pair networks in which the output terminals of one network are connected to the input terminal of the other.
tandem accelerator
A particle nuclear accelerator that derives its name from the two stages of acceleration that particles undergo.

In one version, heavy negatively charged ions are accelerated through one potential difference before being stripped of more electrons and accelerated again in a system using two or more Van de Graaff generators.

Developed by U.S. physicist Robert J. Van de Graaff, 1901-1967; a Van de Graaff generator is an electrostatic generator in which high voltages are produced by a moving belt of insulating material that collects electric charges by induction and discharges them inside a large spherical electrode; used for accelerating electrons, protons, and other nuclear particles.

tandem airplane
An aircraft having two or more seats and/or sets of controls set one behind the other, usually in a tandem cockpit.
tandem duplication
The arrangement of one, or more, identical copies of a segment of DNA; lying one behind the other along a chromosome.
tandem gait
A manner of walking in which the heel of the advancing foot is placed directly in front of the toes of the stationary foot.

It is used to test a patient's equilibrium and coordination.

tandem hoisting
In mining engineering, a method of hoisting used in deep mine shafts in which two skips are employed in one shaft, the lower being suspended from the tail rope of the upper one.
tandem launch
In space technology, the launching of two or more satellites using a single launch vehicle.
tandem mill
In metallurgy, a rolling mill having two or more stands that are arranged to keep metal being processed in a straight line from stand to stand; that is, one behind the other one.
tandem office, tandem central office
In telecommunications, a telephone facility that makes connections between local offices in a region where there are too many such offices to economically establish a full set of direct connections.
tandem propellers
In naval architecture, an arrangement of two propellers on a single shaft.
tandem repeat sequences
Multiple copies of the same DNA base sequence on a chromosome; used as a marker in physical mapping of the chromosome.

Tandem repeats and variable number tandem repeats in DNA occur when a pattern of two or more nucleotides is repeated and the repetitions are directly adjacent to each other.

tandem roller
In mechanical engineering, a road roller with two rolls of similar diameter running on the same tract.
tandem switching
In telecommunications, a type of telephone call routing in which calls travel through one or more intermediate switches to reach their destinations.
tandem system
1. In computer science, a computing system in which there are two central processing units, usually with one controlling the other, and with data proceeding from one processing unit into the other.
2. A system composed of two computers both of which are executing the same problem at the same time.

It may be either a redundant system or a master/slave configuration.