WordNet (r) 3.0 (2006):

RF
    n 1: a substance produced by the hypothalamus that is capable of
         accelerating the secretion of a given hormone by the
         anterior pituitary gland [syn: releasing factor,
         releasing hormone, RF]
    2: a radioactive transuranic element which has been synthesized
       [syn: rutherfordium, Rf, unnilquadium, Unq, element
       104, atomic number 104]
    3: a complex neural network in the central core of the
       brainstem; monitors the state of the body and functions in
       such processes as arousal and sleep and attention and muscle
       tone [syn: reticular formation, RF]

The Free On-line Dictionary of Computing (19 January 2023):

RF

   radio frequency