Military Formation

What word would the Romans have used for the military use of formation (formal name for legions and cohorts)? Online Latin dictionary produces forma, figúra, and conformatió, of which the first two relate closely to physical appearance and the last one relates to many things. Thus, I don't think any of them work well for this usage of the word.
 

AoM

nulli numeri
Only looking through Caesar:

BG 2:
- nullo certo ordine
- sed ratio ordoque agminis (referring to a march)

BC 1:
- sed nullus ordo

BC 2:
- nullo ordine

May not be the best word for 'formation', but I'm not sure. Also worth noting that a translation I found for the second example from BG 2 had ratio as 'arrangement'.
 
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