Meaning of “derby” - Learner’s Dictionary

derby

noun [ C ] uk us /ˈdɑːbi/ US  /ˈdɜːrbi/
SPORT
Derby

a type of horse race

HAT US (mainly UK bowler hat)

a round, hard, black hat worn by men, especially in the past

(Definition of “derby” from the Cambridge Learner’s Dictionary © Cambridge University Press)