Source : Webster's Revised Unabridged Dictionary (1913)

Order \Or"der\, v. t. [imp. & p. p. {Ordered}; p pr. & vb. n.
   {Ordering}.] [From {Order}, n.]
   1. To put in order; to reduce to a methodical arrangement; to
      arrange in a series, or with reference to an end. Hence,
      to regulate; to dispose; to direct; to rule.

            To him that ordereth his conversation aright. --Ps.
                                                  1. 23.

            Warriors old with ordered spear and shield.
                                                  --Milton.

   2. To give an order to; to command; as, to order troops to
      advance.

   3. To give an order for; to secure by an order; as, to order
      a carriage; to order groceries.

   4. (Eccl.) To admit to holy orders; to ordain; to receive
      into the ranks of the ministry.

            These ordered folk be especially titled to God.
                                                  --Chaucer.

            Persons presented to be ordered deacons. --Bk. of
                                                  Com. Prayer.

   {Order arms} (Mil.), the command at which a rifle is brought
      to a position with its but resting on the ground; also,
      the position taken at such a command.

Source : WordNet®

order arms
     n : a position in the manual of arms; the rifle is held
         vertically on the right side with the butt on the ground;
         often used as a command