IPA: //njuːˈmɪzməˌtɪst//
KK: /nʌˈmɪzməˌtɪst/
A person who studies or collects coins and money.
My uncle is a numismatist who has a large collection of rare coins.
Numismatist → It is formed from "numisma" (from Greek "νομίσμα", meaning coin or currency) and "-ist" (meaning one who practices or is concerned with). A numismatist is someone who studies or collects coins and currency.
Think of a numismatist as someone who is deeply interested in 'coins' ('numisma') and is a 'practitioner' ('-ist') of this hobby.
No commonly confused words.