Internet

google

ref

1970s (denoting a computer network connecting two or more smaller networks): from inter- ‘reciprocal, mutual’ + network.

wiktionary

ref

Coined by United States Department of Defense in 1986, as a shortening of  internetwork, from  inter- +‎  network. 

inter- +‎  net

etymonline

ref

internet (n.)

1984, "the linked computer networks of the U.S. Defense Department," shortened from internetwork, inter-network, which was used from 1972 in reference to (then-hypothetical) networks involving many separate computers. From inter- "between" + network (n.). Associated Press style guide decapitalized it from 2016.