Beat

• physics: Beat is the perception of the sum of two close frequencies as one frequency that oscillates between zero intensity and full intensity, caused by the alternating constructive and destructive interference.
• music theory: Beat is any of the periodic transient signals in music that mark the rhythm. DJs often beatmatch the songs that they play.
• literature: Beat is a genre of literature written by beatniks. See: Beat Generation.
• police: Beat is the territory and time that a police officer patrols.
• musical genre: Beat style played in the 1960s