noun
dangerous person; security risk
A person who poses a physical, criminal, or security threat. Often used in law enforcement, security, or warning contexts.
彼は警察から危険人物とみなされている。
He is regarded as a dangerous person by the police.
空港で危険人物リストに載
A person on the security risk list was detained at the airport.
noun
loose cannon
An unpredictable or uncontrollable person whose behavior could cause trouble, especially in an organization or team.
あの新人は何をしでかすかわからない危険人物だ。
That new guy is a loose cannon; you never know what he'll do.