big gunnoun [ C ]
us/ˈbɪɡ ˈɡʌn/also big shot, big wheel, /ˈbɪɡ ˌʃɑt//ˈbɪɡ ˈhwil, ˈwil/someone who has an important or powerful position:
Their lawyer, a big gun from Detroit, commissioned a bunch of surveys to show that their products met the state's standards.