Plain English Meaning
The rule that decides which aircraft gets to keep going and which one has to move out of the way when two aircraft might come into conflict.
Full Definition
The legal entitlement of one aircraft to proceed along its course while other aircraft are required to give way. Right-of-way rules, set out in 14 CFR 91.113, determine which aircraft must yield when paths cross or conflict during flight or on the airport surface.
Context Anchor
You will see this term in airport traffic pattern discussions, especially when deciding which aircraft should continue and which should give way during approach, landing, or pattern entry.
Derivation
From the railway and road-traffic phrase ' of way,' meaning the legal right to pass first. The use carries the same idea: one party has the right to proceed, the other must yield.