1588, "a master of language, one who uses his tongue freely," from L. lingua "language, tongue" (see lingual). Meaning "a student of language" first attested 1641. Linguistics "the science of languages" is from 1847. The use of linguistic to mean "of or pertaining to language or languages" is "hardly justifiable etymologically," according to OED, but "has arisen because lingual suggests irrelevant associations."
[ling-gwist] 
ghū- in Indo-European roots + -ist.]
gwɪst