"between or relating to two languages," 1854, from inter- "between" + lingual. Related: Interlingually.
Entries linking to interlingual
inter-
word-forming element used freely in English, "between, among, during," from Latin inter (prep., adv.) "among, between, betwixt, in the midst of" (also used extensively as a prefix), from PIE *enter "between, among" (source also of Sanskrit antar, Old Persian antar "among, between," Greek entera (plural) "intestines," Old Irish eter, Old Welsh ithr "among, between," Gothic undar, Old English under "under"), a comparative of root *en "in."
A living prefix in English from 15c. and used with Germanic as well as Latinate words. Spelled entre- in French; most words borrowed into English in that form were re-spelled 16c. to conform with Latin except entertain, enterprise. In Latin, spelling shifted to intel- before -l-, hence intelligence, etc.
lingual adj.
"of or pertaining to the tongue," 1640s, from Medieval Latin lingualis "of the tongue," from Latin lingua "tongue," also "speech, language," from Old Latin dingua, from PIE *dnghu- "tongue" (source also of Old English tunge "tongue;" see tongue (n.)). Altered in Latin probably in part by association with lingere "to lick." Earlier "tongue-shaped" (c. 1400).