To threaten or menace someone—to intimidate so as to force compliance or create fear.
犯人は被害者を脅かして金を奪った。
The criminal threatened the victim and took their money.
ネットで匿名で人を脅かすのは重大な問題だ。
Threatening people anonymously online is a serious problem.
彼は部下を脅かして無理な要求を通そうとしたが失敗した。
He tried to force unreasonable demands by intimidating his subordinates, but failed.
To startle or frighten someone suddenly; to scare (intransitive/transitive usage of startling).
後ろから急に声をかけられて脅かされた。
I was startled when someone suddenly spoke to me from behind.
子どもを驚かして脅かす遊びは控えたほうがいい。
It's better to avoid games that scare children by startling them.
大きな音に犬が脅かされて逃げ出した。
The dog was frightened by the loud noise and ran away.