What chord is this?

[mshilarious]

I only like the chords that don't sound good. This is just a fourth, how bad could it be? My personal favorite is A-Bb-B, on strings 4,3,2; or as I call it, the fire alarm chord

 

[ggunn]

I don't even know if this can be called true in the strictest sense, but it's hardly true in the practical sense.

If you ask 100 musicians what chord C-E-G is, they're all going to tell you "C major" (or just "C") if they know any theory at all.

It's true in the strictest sense, because C-E-G can be called three different things, depending on whether you define the C, the E, or the G as the root. Granted, in that simple example it would be silly to call it anything else but a C chord, but when you go off stacking thirds, etc. with the root not necessarily on the bottom, things are not so clear cut.

 

[Henry Mars]

As has been pointed out already, he was only referring to the 2 fretted notes and not the open strings, but I just thought I'd point out one thing in reference to your post.

The chord would be a Cmaj9, not a Cmaj7(add 9).

Cmaj9 implies that you have a 7th. You use "add 9" when there's no 7th.

You are correct by common notation. One of the things that I have learned over many years though is to study the piano chart because what is notated in the chord symbols isn't actually what is being played. The reason why I wrote it that way is for clarity you would be surprised at the number of people that don't know that. In many cases I will notate C7+4 instead of C7b5 depending on the way the harmony is moving.