Pizzicato is plucking the strings of a bowed instrument with the fingers instead of using the bow.
Pizzicato (Italian: 'plucked') is the technique of producing sound on a bowed string instrument — violin, viola, cello, double bass — by plucking the string with the finger rather than drawing the bow across it. Monteverdi was using it as early as 1624 in 'Il combattimento di Tancredi e Clorinda' to imitate the clash of swords. Tchaikovsky wrote an entire movement of his Fourth Symphony (1878) for pizzicato strings — a sound he likened to drunken peasants in conversation. Bartók devised an aggressive variant, the 'snap pizzicato' or Bartók pizzicato, in which the string is pulled away from the fingerboard so it slaps back loudly. In jazz double bass, pizzicato is the default; classical players use it for colour, lightness, and rhythmic drive. Marking 'arco' returns the player to the bow.