Glossary of Terms
 
  dBm  
  An abbreviation for decibels per milliwatt1) Decibels of audio power present compared to one milliwatt of power in a 600 Ohm load.
2) Incorrectly (and commonly) used to designate the reference voltage of .775 volts of audio signal strength regardless of impedance.
 
  Source: Recording Institute of Detroit  

Related terms:
  decibel   watt