In slang, a "troll" is a person who purposely upsets others on the internet

I've always associated it with internet-trolling (including derivates like "concern trolling", "copyright trolling" [cfr. https://darkpsychology.co/troll/]), but lately I hear it a lot as a synonym for looking for a sexual partner, e.g. girls going out "trolling for peen" (#2dopequeens), quite a deviation.

Taki's meaning is the only slang meaning I know. There's also a recent colloquial use to mean "slowly doing a long, aimless search for something that might not be there." For example, "I don't think I have that file on my computer; do you really want me to troll through a million files to see if I can find it?" I've heard people use both the word "troll" (which means moving a boat very slowly through the water in search of fish) and "trawl" (unselectively fishing by dragging a big net along the sea floor).