1each of the two upper limbs of the human body from the shoulder to the hand:she held the baby in her arms
a flexible limb of an invertebrate animal, e.g. an octopus.
a sleeve of a garment.
an ability to bowl, pitch, or throw a ball skilfully:he has a good arm
used to refer to the holding of a person’s arm in support or companionship:as they walked he offered her his armhe arrived with a pretty girl on his arm
used to refer to something powerful or protective:they have extended the arm of friendship to developing countries
2a thing resembling an arm in form or function, in particular:
a side part of a chair or other seat on which a sitter can rest their arm:his right elbow was leaning on the arm of the chair
a narrow strip of water or land projecting from a larger body:a lake which was really an arm of the sea
3a branch or division of a company or organization:the political arm of the separatist group
each of the types of troops of which an army is composed, such as infantry or artillery.