unspecified; indeterminate; not fixed to a specific person or thing (often used in phrases like "an unspecified majority").
不特定多数に向けた広告が最近問題視されている。
Ads targeted at an unspecified mass audience have recently come under scrutiny.
不特定の相手からメールが来ることがあるので注意が必要だ。
You need to be careful because you may receive emails from unspecified senders.
不特定な条件では正確な予測は難しい。
It's difficult to make accurate predictions under unspecified conditions.