arm

Etymology 1

From Middle English arm, from Old English earm, from Proto-West Germanic *arm, from Proto-Germanic *armaz (“arm”), from Proto-Indo-European *h₂(e)rmos (“a fitting, joint; arm, forequarter”), a suffixed form of *h₂er- (“to join, fit together”). cognates Akin to Dutch arm, German Arm, Yiddish אָרעם (orem), Danish, Norwegian and Swedish arm. Indo-European cognates include Latin armus (“the uppermost part of the arm, shoulder”), Armenian արմունկ (armunk, “elbow”), Ancient Greek ἁρμός (harmós, “joint, shoulder”) and ἅρμα (hárma, “wagon, chariot”), Avestan 𐬀𐬭𐬨𐬀 (arma), Old Persian [script needed]|[Term?] (arma).

noun

1. The portion of the upper human appendage, from the shoulder to the wrist and sometimes including the hand.
   She stood with her right arm extended and her palm forward to indicate “Stop!”
   When Timothy and Julia hurried up the staircase to the bedroom floor, where a considerable commotion was taking place, Tim took Barry Leach with him. He had him gripped firmly by the arm, since he felt it was not safe to let him loose, and he had no immediate idea what to do with him. 1963, Margery Allingham, chapter 19, in The China Governess
2. (anatomy) The extended portion of the upper limb, from the shoulder to the elbow.
   The arm and forearm are parts of the upper limb in the human body.
3. A limb, or locomotive or prehensile organ, of an invertebrate animal.
   the arms of an octopus
4. The part of a piece of clothing that covers the arm.
   […] he noticed that a dark stain had appeared under the arm of her grey silk dress. 1970, J. G. Farrell, Troubles, New York: Knopf, published 1971, page 340
5. A long, narrow, more or less rigid part of an object extending from the main part or centre of the object, such as the arm of an armchair, a crane, a pair of spectacles or a pair of compasses.
   The robot arm reached out and placed the part on the assembly line.
6. (geography) A bay or inlet off a main body of water.
   Shelburne Bay is an arm of Lake Champlain.
7. A branch of an organization.
   the cavalry arm of the military service
   Congress has asked the Government Accountability Office, its investigative arm, to review the workplace complaints raised by air marshals, said Charles Young, a spokesman for the office. 2018-04-25, Ron Nixon, “Scandals and Investigations, but Few Arrests, for Air Marshals Program”, in The New York Times
8. (figurative) Power; might; strength; support.
   the arm of the law
   the secular arm
9. (baseball, slang) A pitcher
   The team needs to sign another arm in the offseason.
10. (genetics) One of the two parts of a chromosome.
11. A group of patients in a medical trial.

verb

1. (obsolete) To take by the arm; to take up in one's arms.

Etymology 2

From Middle English arm (“poor, wretched”), from Old English earm (“poor, miserable, pitiful, wretched”), from Proto-West Germanic *arm, from Proto-Germanic *armaz (“poor”), from Proto-Indo-European *h₁erm- (“poor, ill”). cognates Akin to Dutch arm (“poor”), German arm (“poor”), Yiddish אָרעם (orem, “poor”), Swedish arm (“poor”).

adj

1. (UK dialectal, chiefly Scotland) Poor; lacking in riches or wealth.
2. (UK dialectal, chiefly Scotland) To be pitied; pitiful; wretched.

Etymology 3

Back-formation from arms (plural), from Middle English armes, from Old French armes, from Latin arma (“weapons”), from Proto-Indo-European *h₂er-mo-, a suffixed form of *h₂er- (“to fit together”), hence ultimately cognate with etymology 1.

noun

1. (usually used in the plural) A weapon.
   A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed. 1789, Second Amendment to the United States Constitution
2. (in the plural) Heraldic bearings or insignia.
   The Duke's arms were a sable gryphon rampant on an argent field.
3. (in the plural, obsolete) War; hostilities; deeds or exploits of war.

verb

1. (transitive) To supply with armour or (later especially) weapons.
   The king armed his knights with swords and shields.
   They were arming them with spears and shields, putting iron halfhelms on their heads, and arraying them along the inner wall, a rank of snowy sentinels. "Lord Winter has joined us with his levies," one of the sentries [said]. 2015, George R. R. Martin, A Dance with Dragons, Bantam, page 593
2. (transitive, figurative) To supply with the equipment, knowledge, authority, or other tools needed for a particular task; to furnish with capability; to equip.
   Many following him, and, in his journeyings, he visited many at their houses, and gave them consolation, arming them with steady resolves, to be patient in suffering and trust to God for their reward; […] 1801(?), John Bunyan, The Pilgrim's Progress ... to which is Added, the Life and Death of the Author, page 359
   [God] directed them to choose out three hundred only, and, arming them with nothing but trumpets and lamps, to send them by night into the camp of the Midianites. 1885, United States Congressional Serial Set, page 119: Q. In other words, you were commissioning men here in Cincinnati to attend the polls, arming them with authority to arrest citizens; men from outside of the city of Cincinnati to arrest citizens of the city of Cincinnati […] 2011, Meredith H. Lair, Armed with Abundance: Consumerism & Soldiering in the Vietnam War, Univ of North Carolina Press: , →ISBN, page 215: Picture taking soothed support troops' anxieties twice over, empowering them as they navigated a strange environment, and arming them with proof that they really had served in a war. 1806, William turner, An Abstract of the History of the Bible ... With questions for examination, etc, page 43
   […] and arming them with skills, work habits, and inner confidence that no one can ever take away. 2014, Susan Fawcett, Grassroots with Readings: The Writer's Workbook, Cengage Learning, page 466
3. (transitive) To prepare (a tool, weapon, or system) for action; to activate.
   Remember to arm the alarm system before leaving for work.
4. (intransitive, of a tool, weapon, or system) To become prepared for action; to activate.
   Torpedoes were loosed, but the range was too short for them to actually arm, and they bounced harmlessly off the ship as it cut loose with its secondary and antiaircraft guns, smashing anything that it could see. 10 March 2021, Drachinifel, 14:43 from the start, in Guadalcanal Campaign - The Big Night Battle: Night 1 (IJN 3(?) : 2 USN), archived from the original on 2022-10-17
5. (transitive) To cover or furnish with a plate, or with whatever will add strength, force, security, or efficiency.
   to arm the hit of a sword; to arm a hook in angling
6. (intransitive) To take up weapons; to arm oneself.
7. (transitive) To fit (a magnet) with an armature.