One who roves about for prey; one who prowls.(noun)
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Use "prowler" in a sentence
"Generalising this point we can say that the same event can be referred to under quite disparate descriptions: the event of alerting the prowler is the same event as my flipping the light switch which is the same event as my moving of my body (or a part of my body) in a certain way."
"You think the prowler is a figment of my imagination."
"Two other unicorns lay on the ground, dead, and behind the prowler was the dark shape of its mate lying lifelessly in the grass."