IVsus roman degree
The suspended subdominant — the 4th floats over IV, airing out that already-open degree even further before the 3rd resolves.
Where it lives
5semitones from the tonic
Major mode
suspended
Hear it in context: I-IVsus-IV-V
Piano sound loads on first tap. Resolved in the key of C — every chord links to its full analysis.