From Longman Dictionary of Contemporary Englishbig/top gunbig/top gunAmerican English informal someone who is very important within an organization Jed wanted to impress a Harvard professor and some other big guns. → gun
Examples from the Corpus
big/top gun• There was a tank with a big gun on it.• He won't be the last big gun brought out in the battle for Stockton South.• In part two: Showdown: Soccer's big guns prepare for a shootout.• All the big guns are through to the semi-finals as expected.• Lincoln brought in the big guns of William Temple to get bishop and rector to release the curate before the time.• In Houston, many of the big gun shops have opted to police themselves.• They leaned into their big guns, shoulders twitching. 