noun

• (US, military, aviation) reconnaissance fighter; an unarmed fighter modified for photo-reconnaissance (prefix)
• Initialism of right foot.
• (photography) Initialism of range finder.
• (electronics, physics) Initialism of radio frequency. [(uncountable) That part of the electromagnetic spectrum, between about 3 kHz and 300 MHz, within which radio waves are transmitted.]
• (pathology) Initialism of rheumatoid factor. [(immunology) An autoantibody directed against the Fc fragment of immunoglobulin G (IgG), often elevated in certain conditions including rheumatoid arthritis and Sjögren's syndrome.]
• (military, engineering, slang) Initialism of ratfuck (“dirty rick or act of sabotage or interference”). [(vulgar) Someone who engages in dirty tricks.]
• (baseball) Initialism of right field or right fielder.
• (optics, imaging, photography) Abbreviation of radiance field.
• Initialism of Russian Federation. [Alternative formal name of Russia.]
• Initialism of radio frequency. [(uncountable) That part of the electromagnetic spectrum, between about 3 kHz and 300 MHz, within which radio waves are transmitted.]