If something happens indeterminately, you cannot pin it down: you cannot say exactly when, where, how much, or which way. It is the adverb from indeterminate — not fixed, not clearly decided, not possible to know for sure. A scientist might say a measurement is known only indeterminately; a vague answer might be described the same way. The word is formal and a little academic. Everyday English more often says “in an unclear way” or “not exactly.” People sometimes stretch it to mean “for an unknown length of time,” but that job usually belongs to indefinitely (with no set end). Indeterminately is about not being able to know the facts precisely, not about time going on and on.

不確定地；無法確切地（偏書面；日常較常說「不清楚」「沒辦法確定」）