1
general::
Phrase(s): on the prowl
looking for someone for sexual purposes. (Alludes to a prowling cat.) • Tom looks like he is on the prowl again tonight. • That whole gang of boys is on the prowl. Watch out.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Actively looking for something, as in Their underpaid computer programmers are always on the prowl for better jobs. This idiom transfers an animal's search for prey to human pursuits that are usually less bloodthirsty. [c. 1800]
American Heritage Idioms