IPA: /nɒnˈrɪfʌndəbl/
KK: /nɑnˈrɪfʌndəbl/
This word describes something that cannot be returned for a refund or is not eligible to get money back after a purchase.
The ticket I bought is nonrefundable, so I can't get my money back if I change my plans.
Nonrefundable → It is formed from "non-" (meaning not) and "refundable" (from "refund" which is composed of "re-" meaning again and "fundere" meaning to pour). The word "nonrefundable" means that something cannot be poured back or returned, indicating that a payment cannot be refunded.
Think of 'not' ('non-') being combined with 'able to be returned' ('refundable') — so nonrefundable means it cannot be returned.