[arm] n [ME, fr. OE earm; akin to L armus shoulder, Skt irma arm] (bef. 12c) 1: a human upper limb; esp: the part between the shoulder and the wrist
2: something like or corresponding to an arm: 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 usu. 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 ~ 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 baseball well; also: a player having such ability 9: a functional division of a group, organization, institution, or activity "the logistical ~ of the air force " -- arm.less adj -- arm.like adj -- arm in arm : with arms linked together "walked down the street arm in arm"
[2]arm vb [ME armen, fr. OF armer, fr. L armare, fr. arma weapons, tools; akin to L ars skill, Gk harmos joint, arariskein to fit] vt (12c) 1: to furnish or equip with weapons
2: to furnish with something that strengthens or protects
3: to fortify morally
4: to equip or ready for action or operation "~ a bomb" ~ vi: to prepare oneself for struggle or resistance [3]arm n, often attrib [ME armes (pl.) weapons, fr. OF, fr. L arma] (13c) 1 a: a means (as a weapon) of offense or defense; esp: firearm b: a combat branch (as of an army) c: an organized branch of national defense (as the navy)
2. pl a: the hereditary heraldic devices of a family b: heraldic devices adopted by a government 3 pl a: active hostilities: warfare b: military service -- up in arms : aroused and ready to undertake hostilities