Dictograph

[ dik-tuh-graf, -grahf ]
/ ˈdɪk təˌgræf, -ˌgrɑf /

Trademark.

a brand name for a telephonic device with a highly sensitive transmitter obviating the necessity of a mouthpiece: used for listening to conversations secretly or obtaining a record of them.

Example sentences from the Web for dictograph

British Dictionary definitions for dictograph

Dictograph
/ (ˈdɪktəˌɡrɑːf, -ˌɡræf) /

noun

trademark a telephonic instrument for secretly monitoring or recording conversations by means of a small, sensitive, and often concealed microphone