What is "under arms"

Arms \Arms\, n. pl. [OE. armes, F. arme, pl. armes, fr. L. arma, pl., arms, orig. fittings, akin to armus shoulder, and E. arm. See Arm, n.]

1. Instruments or weapons of offense or defense.

   He lays down his arms, but not his wiles.
   --Milton.

   Three horses and three goodly suits of arms.
   --Tennyson.

2. The deeds or exploits of war; military service or science. ``Arms and the man I sing.''
   --Dryden.

3. (Law) Anything which a man takes in his hand in anger, to strike or assault another with; an aggressive weapon.
   --Cowell. Blackstone.

4. (Her.) The ensigns armorial of a family, consisting of figures and colors borne in shields, banners, etc., as marks of dignity and distinction, and descending from father to son.

5. (Falconry) The legs of a hawk from the thigh to the foot.
   --Halliwell.

   Bred to arms, educated to the profession of a soldier.

   In arms, armed for war; in a state of hostility.

   Small arms, portable firearms known as muskets, rifles, carbines, pistols, etc.

   A stand of arms, a complete set for one soldier, as a musket, bayonet, cartridge box and belt; frequently, the musket and bayonet alone.

   To arms! a summons to war or battle.

   Under arms, armed and equipped and in readiness for battle, or for a military parade.

   Arm's end,

   Arm's length,

   Arm's reach. See under Arm.

Under \Un"der\, prep. [AS. under, prep. & adv.; akin to OFries. under, OS. undar, D. onder, G. unter, OHG. untar, Icel. undir, Sw. & Dan. under, Goth. undar, L. infra below, inferior lower, Skr. adhas below. [root]20

1. Cf. Inferior.] 1. Below or lower, in place or position, with the idea of being covered; lower than; beneath; -- opposed to over; as, he stood under a tree; the carriage is under cover; a cellar extends under the whole house.

   Fruit put in bottles, and the bottles let down into wells under water, will keep long.
   --Bacon.

   Be gathered now, ye waters under heaven, Into one place.
   --Milton.

2. Hence, in many figurative uses which may be classified as follows;

   1. Denoting relation to some thing or person that is superior, weighs upon, oppresses, bows down, governs, directs, influences powerfully, or the like, in a relation of subjection, subordination, obligation, liability, or the like; as, to travel under a heavy load; to live under extreme oppression; to have fortitude under the evils of life; to have patience under pain, or under misfortunes; to behave like a Christian under reproaches and injuries; under the pains and penalties of the law; the condition under which one enters upon an office; under the necessity of obeying the laws; under vows of chastity.

      Both Jews and Gentiles . . . are all under sin.
      --Rom. iii. 9.

      That led the embattled seraphim to war Under thy conduct.
      --Milton.

      Who have their provand Only for bearing burdens, and sore blows For sinking under them.
      --Shak.

   2. Denoting relation to something that exceeds in rank or degree, in number, size, weight, age, or the like; in a relation of the less to the greater, of inferiority, or of falling short.

      Three sons he dying left under age.
      --Spenser.

      Medicines take effect sometimes under, and sometimes above, the natural proportion of their virtue.
      --Hooker.

      There are several hundred parishes in England under twenty pounds a year.
      --Swift.

      It was too great an honor for any man under a duke.
      --Addison.

      Note: Hence, it sometimes means at, with, or for, less than; as, he would not sell the horse under sixty dollars.

      Several young men could never leave the pulpit under half a dozen conceits.
      --Swift.

   3. Denoting relation to something that comprehends or includes, that represents or designates, that furnishes a cover, pretext, pretense, or the like; as, he betrayed him under the guise of friendship; Morpheus is represented under the figure of a boy asleep.

      A crew who, under names of old renown . . . abused Fanatic Egypt.
      --Milton.

      Mr. Duke may be mentioned under the double capacity of a poet and a divine.
      --Felton.

      Under this head may come in the several contests and wars betwixt popes and the secular princes.
      --C. Leslie.

   4. Less specifically, denoting the relation of being subject, of undergoing regard, treatment, or the like; as, a bill under discussion. Abject and lost, lay these, covering the flood, Under amazement of their hideous change. --Milton. Under arms. (Mil.)

      1. Drawn up fully armed and equipped.

      2. Enrolled for military service; as, the state has a million men under arms. Under canvas.

         1. (Naut.) Moved or propelled by sails; -- said of any vessel with her sail set, but especially of a steamer using her sails only, as distinguished from one under steam. Under steam and canvas signifies that a vessel is using both means of propulsion.

         2. (Mil.) Provided with, or sheltered in, tents. Under fire, exposed to an enemy's fire; taking part in a battle or general engagement. Under foot. See under Foot, n. Under ground, below the surface of the ground. Under one's signature, with one's signature or name subscribed; attested or confirmed by one's signature. Cf. the second Note under Over, prep. Under sail. (Naut.)

            1. With anchor up, and under the influence of sails; moved by sails; in motion.

            2. With sails set, though the anchor is down.

      3. Same as Under canvas (a), above.
         --Totten.

         Under sentence, having had one's sentence pronounced.

         Under the breath, with low voice; very softly.

         Under the lee (Naut.), to the leeward; as, under the lee of the land.

         Under the rose. See under Rose, n.

         Under water, below the surface of the water.

         Under way, or Under weigh (Naut.), in a condition to make progress; having started.

adv. armed and prepared for fighting

Under arms describes a state of military readiness (actual or ceremonial). Typically, troops are considered "under arms" when they are in uniform, on duty, and carrying a weapon (rifle, side-arm, or sword), as opposed to being in uniform, on duty, but not carrying a weapon.

Soldiers not actually carrying a weapon but wearing a service belt or web gear associated with carrying weapons may be considered to be symbolically "under arms".

Soldiers normally remove headgear while indoors; however, soldiers who are under arms normally wear their headgear indoors, with a few exceptions.