A formation of people or things one behind another WordNet 3.0 & Open English WordNet

A more-or-less straight sequence of people, objects, etc., either arranged as a queue or column and often waiting to be processed or dealt with, or arranged abreast of one another in a row (and contrasted with a column), as in a military formation. Wiktionary

Straight sequence of people, queue. Wiktionary (translation)