tandem

thumb|Horses hitched in tandem pulling a carriage Tandem, or in tandem, is an arrangement in which two or more animals, machines, or people are lined up one behind another, all facing in the same direction. Tandem can also be used more generally to refer to any group of persons or objects working together, not necessarily in line.

The English word tandem derives from the Latin adverb , meaning at length or finally. It is a word play, using the Latin phrase (referring to time, not position) for English "at length, lengthwise".