noun
prospect; likely candidate; something in mind
Refers to a person, thing, or plan that one has in mind as a target or likely choice. Often used in the phrase 目星をつける (to have an idea or to identify a likely candidate).
犯人の目星はついている。
We have a suspect in mind.
次の旅行先の目星をつけておいて。
Think about where you'd like to go for the next trip.
目当て is a more common word for 'aim' or 'objective', often used for concrete goals or targets. 目星 is more about having a rough idea or a likely candidate in mind, and is frequently used in the set phrase 目星をつける.
Compound of 目 (eye) and 星 (star), literally 'eye-star'. The exact origin is uncertain, but it likely developed from the idea of fixing one's gaze on a target, like a star used for navigation.