Pronounced: koh-EE-vuhl, adj
Notes: With the pronunciation, it sounds as if it were somehow evil, but it isn’t.
The word trombenik means “a lazy or a boastful person”
The word comes from Yiddish tromba (trumpet, horn) [see, I was close with my guess of trombone-RL] combined with -nik, a suffix that denotes a person associated with a particular quality, group, etc… such as a neatnik. Getting back to trombenik, it is the equivalent of the phrase tooting one own’s horn.
This is a (relatively) more recent word, first showing up in the early 1930s