arm
[ahrm] 3. a slender part or extension that projects from a main structure.
brawny arm a hard, swollen condition of the arm due to lymphedema following mastectomy.
chromosome arm either of the two segments of the chromosome separated by the centromere. The arms are equal in length when the centromere is in the median position and are unequal when the centromere is off center; the symbol p indicates the short arm and q the long arm.

Chromosome arms. From Dorland's, 2000.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.