by 1937 in reference to electrical transmission of sound and other signals, contracted from modulator-demodulator; see modulator.
Entries linking to modem
modulator n.
c. 1500, "one who or that which modulates," from Latin modulator "one who measures by rule, a regulator" in various senses (such as "musical director"), agent noun from past participle stem of modulari "regulate, measure off properly" (see modulate). Meaning "device that produces modulation of a wave" is from 1919.