Ian, give us the chord progression. Or post a picture of the song so we can see the chord progression.

Mario is correct, there is no such symbol* in music notation of chords.

It could be that the program doing the printing could not reproduce the small circle for Diminished, or the small circle with a diagonal line that is Half-Diminished. Or as Andrew said, less likely, the triangle that means Major 7th.

Show us the song.

* unless it's something like this, where it could mean there is an explanation of the chord somewhere else. I've seen this done when the exact voicing of a chord is needed because there is no standard name for it.

Joke overheard that was said by young music students:
"There are five types of chords - major, minor, suspended, augmented, and demolished."

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