IPA: /ʌnˈmɒnɪtəd/
KK: /ʌnˈmɒnɪtərd/
Not watched or checked regularly; not under observation.
The children played in the park without any unmonitored activities.
Unmonitored → It is formed from "un-" (meaning not) and "monitored" (from Latin "monere", meaning to warn or advise). The word "unmonitored" means not being watched or advised over a period of time.
Think of 'not' ('un-') being 'watched' or 'advised' ('monere') — that's why unmonitored means something is not being overseen.