1. rf - Noun
2. Rf - Proper noun
a radioactive transuranic element which has been synthesized
a substance produced by the hypothalamus that is capable of accelerating the secretion of a given hormone by the anterior pituitary gland
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
Source: WordNet