What does the abbreviation “RF” mean?

In amateur radio, the abbreviation "RF" stands for Radio Frequency. It is a general term used to describe alternating current electrical signals or electromagnetic waves that fall anywhere within the radio spectrum, typically from about 3 kHz up to 300 GHz. While "resonant frequency" is also an important concept in radio engineering and happens to start with the same letters, RF is universally used to refer to radio frequency signals of all types. The other distractors are made-up terms designed to sound technical.