-arm-

WordReference Random House Learner's Dictionary of American English © 2025

arm¹ /ɑrm/   n. [countable]

1. Anatomy
   • the upper limb of the human body.
   • the upper limb from shoulder to elbow:
     The doctor gave me an injection in the arm.
2. Sound Reproduction any part or attachment that resembles an arm, as a projecting support on a chair.
3. a branch, section, or part of an organization:
   an arm of the government.

Idioms

4. Idioms an arm and a leg, a great deal of money:
   That will cost an arm and a leg.
5. Idioms arm in arm, with arms linked together or intertwined:
   walking along arm in arm.
6. Idioms at arm's length, at a distance that discourages intimacy:
   kept her associates at arm's length.
7. (long) arm of the law, the power or authority of the law or law enforcement.
8. Idioms twist someone's arm, to bring strong pressure to bear on someone.
9. Idioms with open arms, cordially;
   hospitably:
   welcomed her with open arms.

arm² /ɑrm/   n. 

[countable]
1. Military Usually, arms. [plural] weapons, esp. guns, rifles, or firearms.
2. Heraldry arms, [plural] the heraldic designs or symbols on a shield.

v. 

3. to (cause to) be equipped with weapons: [no object]
   The country is arming for war.
   [~ + oneself]
   The rebels armed themselves.
   [~ + object]
   They armed their troops.
4. to activate, equip, or prepare (something) for specific purpose or effective use:
   [~ + object] to arm the security system.

Idioms

5. Idioms, Military bear arms:
   • to carry weapons:
     claimed the right to bear arms.
   • to serve as a member of the armed forces:
     He had to bear arms as a youth of only sixteen.
6. Idioms, Military take up arms, to prepare for or go to war.
7. Idioms, Military under arms, (of troops) trained and equipped for battle.
8. Idioms up in arms, indignant:
   is up in arms about the effort to discredit him.

-arm-, root. 

1. -arm- comes from Latin, where it has the meaning "weapon.'' This meaning is found in such words as: armada, armament, arms, disarmament.

WordReference Random House Unabridged Dictionary of American English © 2025

arm¹  (ärm), n. 

1. Anatomy the upper limb of the human body, esp. the part extending from the shoulder to the wrist.
2. Anatomy the upper limb from the shoulder to the elbow.
3. Biology the forelimb of any vertebrate.
4. Zoology some part of an organism like or likened to an arm.
5. Sound Reproduction any armlike part or attachment, as the tone arm of a phonograph.
6. a covering for the arm, esp. a sleeve of a garment:
   the arm of a coat.
7. an administrative or operational branch of an organization:
   A special arm of the government will investigate.
8. Nautical, Naval Terms any of the curved or bent pieces of an anchor, terminating in the flukes. See diag. under anchor. 
9. Furniture an armrest.
10. an inlet or cove:
    an arm of the sea.
11. Military a combat branch of the military service, as the infantry, cavalry, or field artillery.
12. power;
    might;
    strength;
    authority:
    the long arm of the law.
13. Printing [Typography.] either of the extensions to the right of the vertical line of a K or upward from the vertical stem of a Y.
14. an arm and a leg, a great deal of money:
    Our night on the town cost us an arm and a leg.
15. arm in arm, with arms linked together or intertwined:
    They walked along arm in arm.
16. at arm's length, not on familiar or friendly terms;
    at a distance:
    He's the kind of person you pity but want to keep at arm's length.
17. in the arms of Morpheus, asleep:
    After a strenuous day, he was soon in the arms of Morpheus.
18. on the arm, [Slang.] free of charge;
    gratis:
    an investigation of policemen who ate lunch on the arm.
19. put the arm on, [Slang.]
    • to solicit or borrow money from:
      She put the arm on me for a generous contribution.
    • to use force or violence on;
      use strong-arm tactics on:
      If they don't cooperate, put the arm on them.
20. twist someone's arm, to use force or coercion on someone.
21. with open arms, cordially;
    with warm hospitality:
    a country that receives immigrants with open arms.

• bef. 900; Middle English; Old English earm; cognate with Gothic arms, Old Norse armr, Old Frisian erm, Dutch, Old Saxon, Old High German arm (German Arm) arm; Latin armus, Serbo-Croatian rȁme, rȁmo shoulder; akin to Sanskrit īrmá, Avestan arəma-, Old Prussian irmo arm; not akin to Latin arma arm²

armed, adj. 
arm′like′, adj. 

arm²  (ärm), n. 

1. Military Usually, arms. weapons, esp. firearms.
2. Heraldry arms, the escutcheon, with its divisions, charges, and tinctures, and the other components forming an achievement that symbolizes and is reserved for a person, family, or corporate body;
   armorial bearings;
   coat of arms.
3. Military bear arms:
   • to carry weapons.
   • to serve as a member of the military or of contending forces:
     His religious convictions kept him from bearing arms, but he served as an ambulance driver with the Red Cross.
4. Military take up arms, to prepare for war;
   go to war:
   to take up arms against the enemy.
5. Military under arms, ready for battle;
   trained and equipped:
   The number of men under arms is no longer the decisive factor in warfare.
6. up in arms, ready to take action;
   indignant;
   outraged:
   There is no need to get up in arms over such a trifle.

v.i. 

7. to enter into a state of hostility or of readiness for war.

v.t. 

8. to equip with weapons:
   to arm the troops.
9. to activate (a fuze) so that it will explode the charge at the time desired.
10. to cover protectively.
11. to provide with whatever will add strength, force, or security;
    support;
    fortify:
    He was armed with statistics and facts.
12. to equip or prepare for any specific purpose or effective use:
    to arm a security system; to arm oneself with persuasive arguments.
13. to prepare for action;
    make fit;
    ready.

• Latin armāre to arm, verb, verbal derivative of arma (plural) tools, weapons (not akin to arm¹); (noun, nominal) Middle English armes (plural) Latin arma, as above
• Anglo-French, Old French armer
• 1200–50 for verb, verbal; 1300–50 for noun, nominal; (verb, verbal) Middle English armen

arm′less, adj. 
Synonyms

• 12. outfit.

Antonyms

• 9. deactivate, disarm.

ARM, 

1. Business adjustable-rate mortgage.

Arm, 

1. Language Varieties Armenian.

Arm., 

1. Language Varieties Armenian.
2. Armorican.

Ar.M., 

1. Master of Architecture.

• Neo-Latin Architecturae Magister