unknown chord

Can anybody tell me what this chord with an ø symbol after F# is? The key signature is E minor.

  • Why so many views? Why so many upvotes?
    – Matt L.
    Commented Jun 13, 2016 at 11:58
  • 1
    @MattL: Presumably because this question made it into the Hot Network Questions sidebar. Commented Jun 13, 2016 at 12:53
  • @IlmariKaronen: Well, yes, but it only gets there if it is kind of 'hot'. I just wonder why ...
    – Matt L.
    Commented Jun 13, 2016 at 13:23

3 Answers 3


A quick Google search which amounted to "what does a circle with a cross through it mean?" turns up this: http://ultimate-guitar.com/forum/archive/index.php?t-637414.html

The answer is: "Ø = half diminished, aka m7b5"

This particular chord is played on piano as

F#, A, C, E

Credit to PianoChord.com

  • That's an odd way to google for this symbol, since the circle doesn't have a cross through it, nor does the post you linked to describe it that way. You could say it's crossed out, or that it has a line (or slash) through it.
    – LarsH
    Commented Jun 13, 2016 at 14:58
  • 3
    @LarsH Ha ha! Well, whatever... I had never seen it before, and the first thing it looked like to me was one of those "no smoking" signs, which I had always described as circles with crosses, and, apparently, someone else did too. ¯\_(ツ)_/¯ Commented Jun 13, 2016 at 15:16

It is indeed half-diminished. A diminished chord has root, m3, b5 and bb7. In F#o it'll be F#, A, C and Eb. The half dim., a.k.a. m7b5 differs only by the m7; E instead of Eb. Its 1st inversion is the root (inversion/position) of Am6.


The symbol you refer to is a minor 7 flat 5 chord, also called half diminished. While reading music, or writing it, it is easier to read the symbol than the longer version which would be F#-7b5. This symbol also represents the sixth scale degree of the melodic minor scale.

  • 1
    I would say you have that backwards. It is a half diminished chord which is sometimes referred to as a minor 7 b5 which is not proper terminology. It would be like calling a minor chord a major b3.
    – Dom
    Commented Jul 9, 2016 at 16:13
  • "All you need to do is tell that person to study the jazz theory book by Mark Levine or any other theory book on the planet which will refer to that cord as a minor seven flat five yes it's half diminished and like all things in music it can be labeled many many different ways. The chord never functions as a diminished chord which is exactly why it is a minor seven flat five which as we know mostly functions as the 2 chord and minor tonality and or simply the two chord in a 2-5 going to a minor chord." This reply comes after consultation with a college music Professor.
    – Gary
    Commented Jul 9, 2016 at 18:29
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    It is a diminished triad with a minor 7th so it always functions as a some kind of diminished chord. It doesn't function in the same way as a fully diminished 7th as that chord has special properties due to its symmetric nature. No one uses that chord like a minor chord. The only reason people use that terminology because it's used sometimes in chord symbols which some people also call the fully diminished chords m6b5 which again isn't proper. Also borrowing from a parallel minor does not give a a chord "minor tonality" it gives the passage minor tonality which doesn't change what it is.
    – Dom
    Commented Jul 9, 2016 at 21:19

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