Letters that make big gun
b, g, n, i, u are letters that make 'big gun'
1 possible definitions for 'big gun'
Under this definition, big gun is a noun and has the following properties:
big wheel, big cheese, big enchilada, big fish, head honcho, big shot, big deal have the same meaning as 'big gun'
'big gun' can be a type of important person, influential person, personage.
'big gun' can be a useage of colloquialism.