Music notation glossary · Intervals
Third
three or four semitones
In the score
What it means
It decides between major and minor: the major third (four semitones, C–E) makes a major chord, the minor third (three, C–E flat) a minor one.
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See AnotonaEvery note on this page is computed, not typed in — following the rule that also makes F# major spell its seventh degree E#, not F.