switchblade

/S W IH1 CH B L EY0 D/
noun
  1. 1

    A folding knife with a blade which opens automatically (under spring pressure) when a button is pressed.

verb
  1. 1

    To attack or cut with a switchblade.

  2. 2

    To spring open or up.

  3. 3

    To (cause to) make a sudden move or transition.

Source: https://en.wiktionary.org/wiki/switchblade