IPA: /nɒnˈdɪplɪtəbl/
KK: /nɑnˈdɪplɪtəbəl/
Something that cannot be used up or exhausted, meaning it can be used indefinitely without running out.
Solar energy is a nondepletable resource that can be harnessed for power.
Nondepletable → It is formed from "non-" (meaning not) and "depletable" (from "deplete" which comes from Latin "deplere", meaning to empty or drain). The word "nondepletable" means not able to be emptied or drained, indicating a resource that cannot be depleted.
Think of 'not' ('non-') being combined with 'draining' ('depletable') to remember that 'nondepletable' refers to something that cannot be drained or used up.