pe·dan·tic [/pəˈdan(t)ik/]
adjective

1: of, relating to, or being a pedant
“a pedantic teacher”

2: narrowly, stodgily, and often ostentatiously learned
“a pedantic insistence that we follow the rules exactly”
“Far worse, he was pedantic, pernickety, letting nothing inaccurate or of uncertain meaning go by—not an aphrodisiac quality.”

3: unimaginative, dull
“Pedantic song choices don’t help any. Only 2 out of 10 songs stray from the most common classic-rock fodder.”

Pedantic can be used as an insulting word used to describe someone who annoys others by correcting small errors, caring too much about minor details, or emphasizing their own expertise especially in some narrow or boring subject matter.

A pedantic person may do lots of annoying things, such as point out minor errors, correct people who make small mistakes, and brag about their own knowledge and expertise.