a human limb; technically the part of the superior limb between the shoulder and the elbow but commonly used to refer to the whole superior limb
"She carefully wrapped her arm in a bandage after falling off her bike."
any instrument or instrumentality used in fighting or hunting
"he was licensed to carry a weapon"
the part of an armchair or sofa that supports the elbow and forearm of a seated person
"He stretched out his hand to steady himself on the worn leather arm as he settled into the old sofa."
a division of some larger or more complex organization
"a branch of Congress"
"botany is a branch of biology"
"the Germanic branch of Indo-European languages"
The portion of the upper human appendage, from the shoulder to the wrist and sometimes including the hand.
"The package arrived in two days thanks to my decision to ship it via Priority Mail Express instead of waiting for standard delivery."
A weapon.
accelerated reply mail: a service of the United States Postal Service
In plain English: An arm is the part of your body that connects your shoulder to your hand and lets you hold things.
"He hurt his arm when he fell off his bike."
Usage: When referring to a person's limb or a weapon, use "arm," but reserve the acronym ARM specifically for the postal service's accelerated reply mail option. Do not confuse the body part or military equipment with this specialized mailing service unless the context is explicitly about USPS delivery speeds.
To take by the arm; to take up in one's arms.
"The king ordered his blacksmiths to arm every knight before they marched out to battle."
To supply with armour or (later especially) weapons.
In plain English: To arm someone means to give them weapons so they can fight.
"She armed herself with a flashlight before going into the dark basement."
Usage: Use "arm" as a verb when you mean to equip someone with weapons or protective gear for defense or combat. Avoid confusing it with the noun referring to a body part unless you are specifically discussing physical limbs.
Poor; lacking in riches or wealth.
"The map showed that most people living near the border in Arm are descendants of refugees who fled decades ago."
Abbreviation of Armenian.
In plain English: When something is described as an arm, it means you can use your hands to hold or carry it easily.
"The long arm reached out from the coat pocket to grab the phone."
Usage: Do not use "arm" as an adjective to mean "Armenian," as this is a specific abbreviation that does not function as a standard modifier in everyday English. Instead, reserve the word for its common descriptive senses related to weapons or limbs when describing nouns.
Initialism of Acorn RISC Machine or Advanced RISC Machine.
"The ARM architecture is widely used in modern smartphones and embedded systems due to its efficiency."
The word "arm" comes from the Old English earm, which traces its roots back to a Proto-Indo-European term meaning a fitting or joint. This ancient concept of a connecting limb eventually evolved into the modern English word for the body part used to hold objects.