Definition of “cowboy” - Learner’s Dictionary

cowboy

noun [ C ] uk us /ˈkaʊbɔɪ/
ANIMAL WORKER

a man whose job is to look after cows in the US, and who usually rides a horse

BAD WORKER UK informal

someone who does their job badly or who is dishonest in business:

cowboy builders

(Definition of “cowboy” from the Cambridge Learner's Dictionary © Cambridge University Press)