When you entrap someone or something, you do not only catch them. You set things up so they walk into the catch — a trap, a trick, a place or a deal they then cannot get out of. People sometimes use it for animals, but much more often for people: a buyer is entrapped into a contract, a suspect is entrapped by the police, a person is entrapped in a situation that was arranged for them. The extra idea, compared with the simple verb trap, is the leading-in. Someone is pulled or fooled into the catch, not only found already in it. It is a fairly formal word. News, courts, and serious writing like it. In everyday talk, people more often say trap, set up, or trick.