IPA: /ˌɛk.səˈnjuː.mi.ə/
KK: /ɛkˈsəʊnʊmiə/
Items that resemble coins but are not legal tender, often collected for their historical or artistic value.
He has a fascinating collection of exonumia, including tokens and medals.
Exonumia is formed from "exo-" (meaning outside) and "numisma" (from Greek, meaning coin). The term refers to items that are similar to coins but are not legal tender, such as tokens or medals, which are found outside the realm of official currency.
Think of 'outside' ('exo-') and 'coin' ('numisma') to remember that exonumia refers to items that resemble coins but are not used as official money.