From WordNet (r) 3.0 (2006):
Rh
n 1: a blood group antigen possessed by Rh-positive people; if
an Rh-negative person receives a blood transfusion from an
Rh-positive person it can result in hemolysis and anemia
[syn: rhesus factor, Rh factor, Rh]
2: a white hard metallic element that is one of the platinum
group and is found in platinum ores; used in alloys with
platinum [syn: rhodium, Rh, atomic number 45]
3: any of several hormones produced in the hypothalamus and
carried by a vein to the anterior pituitary gland where they
stimulate the release of anterior pituitary hormones; each of
these hormones causes the anterior pituitary to secrete a
specific hormone [syn: releasing hormone, RH, releasing
factor, hypothalamic releasing hormone, hypothalamic
releasing factor]