IPA: /nɒnˈkjuːmjʊlətɪv/
KK: /nɑnˈkjuːmjʊlətɪv/
Not adding up or increasing over time; not accumulating.
The noncumulative interest means that you will not earn interest on previously unpaid interest.
Noncumulative → It is formed from "non-" (meaning not) and "cumulare" (meaning to heap or pile up) and the suffix "-ive" (meaning having the nature of). The word "noncumulative" means not having the nature of accumulating or piling up.
Think of 'not' ('non-') and 'piling up' ('cumulare') to remember that 'noncumulative' means something that does not accumulate.