open order
/ˌəʊp(ə)n ˈɔːdə/Chiefly Military
noun
1 Army. A 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).
2 Navy. With in. A formation in which individual ships are spaced at regular intervals, especially at four cables apart. Now rare.
Origin
Early 17th century; earliest use found in Gervase Markham (?1568–1637), author. From open + order.