Definition of open order in English:

open order

Pronunciation /ˌəʊp(ə)n ˈɔːdə/

noun

Military
  • 1A formation of regularly spaced men, horses, etc.; especially one in which individual soldiers are two or more yards apart. Usually with preceding in (also † at).

  • 2rare With in. A formation in which individual ships are spaced at regular intervals, especially at four cables apart.

Origin

Early 17th century; earliest use found in Gervase Markham (?1568–1637), author. From open + order.