sus chord
A chord in which the third is replaced by either the fourth (sus4) or the second (sus2), creating a sense of unresolved tension
In Depth
Suspended chords remove the note that defines major or minor quality, replacing it with a note that wants to resolve back. A Csus4 contains C-F-G; the F pulls toward E, resolving to a C major triad. A Csus2 contains C-D-G; the D can move to either E or E♭. In classical theory, the sus4 is a true suspension that must resolve. In pop and rock, sus chords often stand alone as stable sonorities, prized for their open, ambiguous quality. The Who's Pete Townshend built an entire guitar style around sus chords.
The opening chord of A Hard Day's Night by the Beatles has been analysed as containing multiple suspended elements — it took musicologists decades to agree on what notes George Harrison actually played.