Select the most appropriate meaning of the given idiom.

Pipe dream

A dream or idea that is unlikely to happen

The most appropriate meaning of the idiom "pipe dream" is (3) A dream or idea that is unlikely to happen.

The other options do not fit the meaning of the idiom.

• A dream or idea that keeps getting repeated can be a pet peeve or a mantra.
• A dream or idea that is loudly proclaimed can be a declaration or a manifesto.
• A dream or idea that is nearly accomplished is a possibility or a near miss.