—arm /ɑːm/ aep /ɑːrm/
noun (BODY PART)
A1 [C] either of the two long parts of the upper body that are fixed to the shoulders and have the hands at the end:
» My arms ache from carrying this bag.» She put/threw her arms round me and gave me a hug.» He took/held her in his arms (= held her closely).» Bill arrived at the party with his new girlfriend on his arm (= her hand resting on his arm).See picture: a person's arm 
See picture: upper arm
Thesaurus+: ↑The arm
C2 [C] The arm of a piece of clothing or furniture is a part of it that you put your arm in or on:
» the arm of a jacket» the arm of a chairSee picture: arm/sleeve of a jacket Thesaurus+: ↑Parts of clothesThesaurus+: ↑Chairs and seatsarm in arm
C2 When two people are arm in arm, they both have one arm bent at the elbow and passing around and supporting, or being supported by, the arm of the other person:
» We walked arm in arm along the river bank.Thesaurus+: ↑Having in your hands• • •
Extra Examples:» Her arm was bandaged from the elbow to the fingers.» Without saying a word, she took hold of my arm and marched me off to the headmaster's office.» He put his arm around her shoulder protectively.» He ran up to her, his arms outstretched.» She sat back in her chair and wrapped her arms around her knees.noun (WEAPONS)
arms [plural]► F0 weapons and equipment used to kill and injure people: » They have been charged with supplying arms to the guerrillas.» An arms cache was discovered in South Wales.» The minister has called on the terrorists to lay down their arms (= stop fighting).» They are willing to take up arms (= prepare to fight) (against the government) if they have to.See picture: arms Thesaurus+: ↑Arms and munitions in general
noun [C] (OF LAND/WATER)
► F0 An arm of land or water is a long, thin part of it that is joined to a larger area.Thesaurus+: ↑Bays and gulfs , ↑Coasts and beachesThesaurus+: ↑Promontories and peninsulasnoun [C] (OF ORGANIZATION)
► F0 An arm of an organization is a part of it that is responsible for a particular activity or place: » The British company is one arm of a large multinational.Thesaurus+: ↑Societies, clubs and organizationsverb ↑Verb Endings for arm
F0 [I or T] to provide yourself or others with a weapon or weapons:
» Nobody knows who is arming the terrorists.» I armed myself with a baseball bat and went to investigate the noise.» They are currently arming for war.→ OPPOSITE DISARM(Cf. ↑disarm)Thesaurus+: ↑Providing weapons or taking weapons awayC2 [T] to provide yourself or others with equipment or knowledge in order to complete a particular task:
» She armed herself for the interview by finding out all she could about the company in advance.» I went to the meeting armed with the relevant facts and figures.Thesaurus+: ↑Giving, providing and supplying• • •
Extra Examples:» The police have to arm themselves against attack.» In arming the dictator, the US was creating a Frankenstein who would threaten their influence in the region.» Rioters armed with firebombs set light to police barricades.» If he's not armed, don't shoot.» War seemed inevitable and both sides were arming in preparation.