push button
  按鈕
  Push button. Elec. A simple device, resembling a button in form, so arranged that pushing it closes an electric circuit, as of an electric bell; -- called also button.
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  push button
       n : an electrical switch operated by pressing a button; "the
           elevator was operated by push buttons"; "the push beside
           the bed operated a buzzer at the desk" [syn: push, button]