Definition
The ability of a radio receiver to separate a desired signal from other signals on nearby frequencies and reject the unwanted ones. A receiver with high selectivity can lock onto the chosen station while filtering out signals on adjacent channels.
Plain English
How well a radio can pick out the one station you want and ignore everything close to it on the dial.
Context Anchor
Seen in avionics and aircraft radio discussions, especially when comparing how well a receiver separates closely spaced frequencies.
Derivation
From the Latin 'selectus,' meaning 'chosen.' Selectivity is literally the receiver's ability to choose one frequency and reject the rest.
Why Pilots Care
Clear reception of ATC instructions and navigation aids depends on it, especially in congested airspace.
Analogy
It is like listening to one person in a room while ignoring nearby conversations. The better your selectivity, the easier it is to focus on the voice you meant to hear.
Intuition Check
Do not read selectivity as just “being picky” in a general sense. In radio use, it specifically means separating the desired frequency from nearby unwanted frequencies.
Example Sentence 1
The new com radio has better selectivity, so the pilot no longer hears chatter from the adjacent frequency bleeding through.
Example Sentence 2
Low selectivity caused the ADF to pick up an interfering beacon instead of the one tuned for the approach.