- an upper limb of the human body
- in anatomy, the part of the upper limb between the shoulder and the elbow
- in nontechnical use, the part of the upper limb between the shoulder and the wrist
- anything resembling this in structure or function; esp.,
- the forelimb of some vertebrate animals
- any limb of an invertebrate animal
- anything commonly in contact with the human arm; esp.,
- a sleeve of a garment
- a support for the arm on a chair, sofa, etc.
- anything thought of as armlike, esp. in being attached or connected to something larger: an arm of the sea, a yardarm, the arm of a balance, an arm of the government, etc.
- power to seize, control, etc.: the long arm of the law
- ☆ Baseball, Football ability to pitch or throw a ball
ME < OE earm; akin to L armus, Goth arms, OHG arm: see art