IPA: /ʌnˈtaɪmd/
KK: /ʌnˈtaɪmd/
Not measured or limited by time; occurring without a specific time frame.
The exam was untimed, allowing students to work at their own pace.
Untimed → It is formed from "un-" (meaning not) and "time" (from Old English "tima", meaning a period or duration). The word "untimed" means not measured or not restricted by time.
Think of 'not' ('un-') being applied to a 'period' ('tima') — that's why untimed means not restricted by time.