What does a plus sign denote after a chord's name?

Question

Under the Bridge features a chord called 'E7+'

What does this plus sign mean and how is E7+ different to E7? Is this a dominant or augmented chord?

Answer 1

The plus sign means the chord is an augmented one. This means the 5th of it is sharpened by a semitone. The chord in question is normally spelled E G# B and D, (for E7). The augmented chord will have E G# B# (C) and D in it. Yes, dominant, yes, augmented. A really pushy chord to get to A usually.

EDIT!!! Having said all that, I've just listened to it, and the lost chord is actually E MAJOR 7th. E G# B D#. Usually written as Emaj7, or E Δ 7. I guess someone thought that E with a dominant 7 (D) up a fret is augmented, but it's not the usual (or correct imo) way to write it. Simple way to play, - open E, with 4th st. on 1st fret. Sounds better without the top E played.

You can get a reasonable copy of what RHCP play with a barre across top 3 st. 4th fret, and bottom open.

Answer 2

Tim has answered that in the song there is a E maj7 chord and not an augmented one (and he is correct), but let me add something about the augmented chords.

An augmented chord with a minor 7th is usually written as E+ 7 and not E7+. The latter is probably intended to say that the 7th is major, which is written wrong. So, if you want simply to say that the B in the E chord is sharp, use a '+' sign next to the E: E+ 7, or E+ if the chord doesn't have a 7th.

For the chord diagram of a Emaj7 chord, you can search emaj7 in the site you provided and see the results:

(the other two results that are mentioned on top, are some more advanced ones that you won't need in this example).

When Frusciante played with the Peppers, he used the 3rd of the above ways to play the specific part.