IPA: /nɒnˈɪnˌstɔːlmənt/
KK: /nɑnˈɪnˌstɔlmənt/
This term describes something that is paid for in a single payment rather than in parts over time.
The purchase was made with a noninstallment payment, so the full amount was due at once.
Noninstallment → It is formed from "non-" (meaning not) and "installment" (from Old French *instalment*, meaning a portion of a payment). The word "noninstallment" refers to something that is not paid in portions or installments.
Think of 'not' ('non-') paying in 'portions' ('installment') — that's why noninstallment means not in parts.