In music, sharp, dièse (from French), or diesis (from Greek) means higher in pitch and the sharp symbol raises a note by a half tone. Intonation may be flat, sharp, or both, successively or simultaneously. More specifically, in musical notation, sharp means “higher in pitch by a semitone (half step),” and has an associated symbol (), which may be found in key signatures or as an accidental, as may flats. Under twelve-tone equal temperament, B sharp, for instance, sounds the same as, or is enharmonically equivalent to, C natural, and E sharp is enharmonically equivalent to F natural. In other tuning systems, such enharmonic equivalences in general do not exist. To allow extended just intonation, composer Ben Johnston uses a sharp to indicate a note is raised 70.6 cents (ratio 25:24), or a flat to indicate a note is lowered 70.6 cents. In tuning, sharp can also mean “slightly higher in pitch” (by some unspecified amount). If two simultaneous notes are slightly out of tune, the higher-pitched one (assuming the lower one is properly pitched) is said to be sharp with respect to the other. Furthermore, the verb sharpen means “raise the frequency of a note, typically by a small musical interval”. Double sharps also exist; these are denoted by the symbol and raise a note by two semitones, or one whole tone. Less often (in for instance microtonal music notation) one will encounter half, or three-quarter, or otherwise modified, sharps. A half sharp indicates the use of quarter tones, and may be marked with various symbols including . Although very uncommon, a triple sharp () can sometimes be found. It raises a note by three semitones.