Plain English Meaning
The set wording controllers and pilots are expected to use on the radio so messages are short, clear, and never confused with anything else.
Full Definition
The standardized words, phrases, and formats used by air traffic controllers and pilots when communicating by radio. ATC phraseology is defined and published by the FAA so that every transmission carries a precise, agreed meaning that both parties interpret the same way.
Context Anchor
You will see this term in instrument flying when a pilot receives, repeats, or asks about a clearance or instruction from air traffic control.
Derivation
Phraseology comes from the Greek phrasis, meaning a way of speaking. In aviation it refers not just to words used, but to the specific patterns and order of words that have been agreed for radio use.