An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
Ebaug is Eb, G and B — Eb with the fifth raised a semitone.
It sounds stretched, and suspended between keys. Its commonest job is passing between a major triad and its sixth or seventh, with the raised fifth as a single voice walking up.
Passing chord — it belongs to no key in particular.

| Eb | G | B |
|---|---|---|
| 1 | 3 | ♯5 |
Also written Eb+, Eb(#5) or Eb augmented. The same chord either way; which spelling you meet depends on who wrote the chart.
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
Ebaug has 2 of them, on the middle four strings and strings 6-4-3-2, from the 3rd fret up to the 5th — every inversion the chord has: Eb in the bass and G in the bass. The one to learn first is the Eb shape at the 5th fret, which is the easiest grip here.
All 8 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
Every note of Ebaug is in Eb whole tone and Eb altered.
Change one note of Ebaug and you have Eb (the sharp fifth becomes the fifth), Ebmaj7#5 (add the major seventh) or Ebaug7 (add the flat seventh).
Ebaug is a augmented chord — root, major third, sharp fifth. Augmented chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.