1 (Rad) to listen in to sth escuchar algo
don't forget to listen in tomorrow and we'll have one hour of gossip make sure you listen in to Chris Tarrant's Breakfast Show this morning a communications base which could listen in to radio traffic within the USSR itself
2 (eavesdrop) escuchar a scrambler to stop eavesdroppers listening in they can choose their own key to keep other people from listening in
to listen in on or to a conversation escuchar una conversación a hurtadillas
how dare you pick up the phone and listen in on my conversations? will you listen in on the extension in the dining-room? I signed a formal notice to say I would not listen in to telephone conversations what kind of person gets his kicks from listening in to other people's private conversations?
3 (attend, observe) I would like to listen in on or to your discussion me gustaría participar en tu discusión en calidad de oyente
the university had banned him from listening in to other students' tutorial discussions