BPM

From AudioLexic

Short for Beats Per Minute.

BPM is a common way to define tempo in Western music. The second hand on a clock can be said to be moving at 60 bpm, since it evenly ticks at a rate of 60 beats per minute. A tempo of 120 bpm would be twice as fast.

Instead of bpm, the term MM is sometimes used, especially in classical scores, but they mean the same thing. MM stands for Maelzel's Metronome, after its "inventor" Johann Nepomuk Maelzel (1772-1838) who registered the metronome in place of its true inventor Dietrik Nikolaus Winkel (1780-1826).