A critical area of performance for aircraft detection systems, defined by the distance at which the radar beam rises enough above the Earth's surface to make detection of a target at low level impossible.

plural of radar horizon

plural of radical feminism

plural of radio signal

a signal, which can vary in strength due to various factors, transmitted and received by radio by means of radio waves.

A fictional radio station used in a series of political jokes parodying Socialist countries.

plural of face for radio

plural of radiation impedance

(US, historical) A female factory worker who contracted radiation poisoning from luminous paint (containing radium) used in watch dials in the early 20th century.

plural of Radium Girl