arm

1 of 5

noun (1)

plural arms
1
: a human upper limb
especially : the part between the shoulder and the wrist
2
: something like or corresponding to an arm: such as
a
: the forelimb of a vertebrate
b
: a limb of an invertebrate animal
c
: a branch or lateral shoot of a plant
d
: a slender part of a structure, machine, or an instrument projecting from a main part, axis, or fulcrum
e
: the end of a ship's yard
also : the part of an anchor from the crown to the fluke see anchor illustration
f
: any of the usually two parts of a chromosome lateral to the centromere
3
: an inlet of water (as from the sea)
4
: a narrow extension of a larger area, mass, or group
5
: power, might
the long arm of the law
6
: a support (as on a chair) for the elbow and forearm
7
: sleeve
8
: the ability to throw or pitch a ball well
also : a player having such ability
9
: a functional division of a group, organization, institution, or activity
the logistical arm of the air force
10
medical : a group of subjects provided a particular treatment in a clinical trial
Since this trial did not include a radiation-only treatment arm, it has been questioned whether radiation therapy alone might be as effective as sequential chemotherapy and radiation therapy in preserving the larynx.Everett E. Vokes et al.
armless adjective
armlike adjective

arm

2 of 5

verb

armed; arming; arms

transitive verb

1
: to furnish or equip with weapons
2
: to furnish with something that strengthens or protects
arming citizens with the right to vote
3
: to equip or ready for action or operation
arm a bomb

intransitive verb

: to prepare oneself for struggle or resistance
arm for combat

arm

3 of 5

noun (2)

often attributive
1
a
: a means (such as a weapon) of offense or defense
especially : firearm
b
: a combat branch (as of an army)
c
: an organized branch of national defense (such as the navy)
2
arms plural
a
: the hereditary heraldic devices of a family
b
: heraldic devices adopted by a government
3
arms plural
a
: active hostilities : warfare
a call to arms
b
: military service

Arm

4 of 5

abbreviation (1)

Armenian

ARM

5 of 5

abbreviation (2)

adjustable rate mortgage
Phrases
arm in arm
: with arms linked together
up in arms
: aroused and ready to undertake a fight or conflict

Example Sentences

Verb They armed the men for battle. The group of fighters was armed by a foreign government. The two countries have been arming themselves for years, but now they have agreed to disarm. We armed ourselves with the tools we would need to survive in the forest. They arm people with accurate information. arming women with the right to vote Once the bomb has been armed, we have five minutes to escape. See More

Word History

Etymology

Noun (1)

Middle English, going back to Old English earm, arm, going back to Germanic *arma-, masculine, (whence also Old Frisian erm "arm," Old Saxon arm, Old High German aram, arm, Old Norse armr, Gothic arms), going back to Indo-European *h2orH-mo-, whence also Old Church Slavic ramo "shoulder," Bosnian-Croatian-Serbian rȁme, stem rȁmen-, Czech ráměk; a parallel zero-grade *h2r̥H-mó- gives Old Prussian irmo "arm," Lithuanian (eastern dialects) ìrmėdė "pain from gout, chill, fever" (irm- "arm" + -ėdė "eating"), Sanskrit īrmá- "arm," Avestan arəma-; Latin armus "forequarter (of an animal), shoulder" probably goes back to *h2erH-mo-

Note: Usually claimed to be a derivative of the verb *h2er- "fit, join" (see arm entry 3)—very plausible semantically—though the Sanskrit and Baltic forms require a second laryngeal (*h2erH-) in the base (cf. Rix et al., Lexikon der indogermanischen Verben, 2. Auflage, Wiesbaden, 2001, where the verbal base is posited without a second laryngeal). Could the suffix be *-H-mo-? The Slavic noun fluctuates in inflection between -mo- and -men- (see André Vaillant, Grammaire comparée des langues slaves, II:1 [Lyon, 1958], pp. 214-15). According to P. Schrijver, The Reflexes of the Proto-Indo-European Laryngeals in Latin (Amsterdam, 1991), p. 194, Latin armus cannot be traced to *h2r̥H-mo-, which would have yielded *ramus. Regarding Armenian armukn "elbow," see H. K. Martirosyan, Etymological Dictionary of the Armenian Inherited Lexicon, Leiden, 2010, s.v.

Verb

Middle English armen, borrowed from Anglo-French armer, going back to Latin armāre, derivative of arma "implements of war, weapons, equipment" — more at arm entry 3

Noun (2)

Middle English armes (plural), "weapons, the military profession, heraldic devices," borrowed from Anglo-French, plural of arme "weapon," going back to Latin arma (neuter plural) "implements of war, weapons, equipment," derivative, with a suffix *-mo-, from a presumed verbal base *ar-, going back to Indo-European *h2er- "fit, join," whence Greek reduplicated aorist ḗraron "(I) fit together, equipped, fit closely" (from which present tense ararískō, ararískein), ármenos (middle participle) "fitting, suited to," and (with suffixed *-smo- giving initial aspiration?) harmós "joint," hárma, harmat- "chariot, team of horses"; Armenian arari "(I) made," aṙnem "I make"

Note: See also art entry 1, arthro-, article entry 1, artiodactyl.

First Known Use

Noun (1)

before the 12th century, in the meaning defined at sense 1

Verb

13th century, in the meaning defined at transitive sense 2

Noun (2)

13th century, in the meaning defined at sense 1a

Time Traveler
The first known use of arm was before the 12th century

Dictionary Entries Near arm

Cite this Entry

“Arm.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/arm. Accessed 6 Feb. 2023.

Kids Definition

arm

1 of 3 noun
1
a
: a human upper limb
especially : the part between the shoulder and wrist
b
: a corresponding limb of a lower vertebrate animal
2
: something resembling an arm in shape or position
an arm of the sea
the arm of a chair
3
: power entry 1 sense 1a
the long arm of the law
4
armed
ˈärmd
adjective
armless adjective
armlike adjective

arm

2 of 3 verb
1
: to provide with weapons
arm a regiment
2
: to provide with a way of fighting, competing, or succeeding
armed herself with facts
3
: to make ready for action or use
arm a bomb

arm

3 of 3 noun
1
a
: weapon
especially : firearm
b
: a branch of an army
c
: a branch of the military forces
2
plural : the designs on a shield or flag of a family or a government
3
plural
a
: actual fighting : warfare
a call to arms
b
: military service

Medical Definition

arm

noun
1
a
: a human upper limb
b
: the part of the human upper limb between the shoulder and the wrist
also : brachium
2
a
: the forelimb of a vertebrate other than a human being
b
: a limb of an invertebrate animal
c
: any of the usually two parts of a chromosome lateral to the centromere
3
: a group of subjects provided a particular treatment in a clinical trial
Since this trial did not include a radiation-only treatment arm, it has been questioned whether radiation therapy alone might be as effective as sequential chemotherapy and radiation therapy in preserving the larynx.Everett E. Vokes et al., The New England Journal of Medicine

Legal Definition

ARM

abbreviation
adjustable rate mortgage

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