Ab Suspended 4th (Absus4)
Also written as G# Suspended 4th (G# and Ab are the same key).
1+4+5
Notes in Ab Suspended 4th
G# (root)C#D#
Inversions
Same notes as Ab Suspended 4th, with a different chord tone as the lowest note. Useful for smoother movement between chords instead of jumping around the keyboard.
Root position
G# in the bass
1st inversion
C# in the bass (Absus4/C#)
2nd inversion
D# in the bass (Absus4/D#)
Play G#, C# and D# together and you get Ab Suspended 4th.
The other suspension raises the missing third up to a perfect fourth, which sits a half step above where the third would normally be. That closeness creates real tension, and it's why a sus4 chord so often falls straight back down into the plain major or minor triad on the same root a beat later.