A musical prefix is a numeral or other prefix used in music theory, specifically musical tuning.
Prefix Meaning (#) Terms Semi- / Half- 1/2 Semitone, halftone, semicomma, semiditone, semi-augmented (fourth), semi-diminished (fifth) Tri- 3 Tritone, tritonic Sept- 7 Septimal Undec- 11 Undecimal Tridec- 13 Tridecimal Septen- 17 Septendecimal Novendec- 19 Novendecimal Milli- 1000 Millioctave Dia- through Diaschisma, diatessaron, diapente, diapason Di- 2 Diesis, ditone En- to make into, to put into, to get into Enharmonic Apo- away, different from Apotome Im- not Imperfect (fourth) Sesqui- 1-1/2 Sesquioctavan, sesquitertian, sesquialterate
See also Limit (music) List of pitch intervals