modem UK /ˈməʊdəm/US /ˈmoʊdəm/noun 1verb 1forms 5 noun1 •A device that encodes digital computer signals into analog telephone signals and vice versa, allowing computers to communicate over a phone line. verb1 •To transmit by modem.Personal modeming is most prevalent in the U.S., where a modem generally doesn't have huge taxes slapped on it, and after-tax income is comparatively high. — 1992 formsmodemed · modemmed · modeming · modemming · modems