gunner
n. countable C2 Proficiency US //ˈɡənɝ// UK //ɡˈʌnɐ// gun·ner
n. a person whose job is to fire a large gun, especially on a ship or plane. In some schools or offices, it can also mean someone who is too competitive and works too hard to beat others.
n. a member of the armed forces who operates or maintains a large-calibre gun or artillery piece. In North American academic or professional slang, it refers to an overachieving, hyper-competitive individual who seeks to outperform peers at any cost.
The gunner aimed the cannon at the target.
The law school was full of gunners who spent every waking hour in the library to secure the top ranking.
Usage
In its military sense, it is a formal job title; in its academic sense, it is informal and often carries a negative or critical tone.