IPA: /ˈtjuːbəɪst/
KK: /ˈtuːbɪst/
A person who plays the tuba, a large brass musical instrument with a deep sound.
The tubaist performed beautifully during the concert.
Tubaist → It is formed from "tuba" (from Latin *tuba*, meaning trumpet or horn) and "-ist" (meaning one who practices or is concerned with). A tubaist is one who plays the tuba, a brass musical instrument.
Think of a 'tuba' as a type of horn, and remember that a 'tubaist' is someone who plays that horn.