"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).
1753, a type of surgical instrument, from Latin radula "scraper, scraping iron," from radere "to scrape" (see raze (v.). As "tongue or lingual ribbon of a mollusk," by 1853. Related: Radular.
"rough sound of the letter -r-" (especially that common in Northumberland), 1760, later extended to "northern accented speech" in general. Possibly the sound of the word is imitative of the speech peculiarity itself, or it was adapted from one of the senses of bur (q.v.), perhaps from the phrase to have a bur in (one's) throat (late 14c.), which was a figure of speech for "feel a choking sensation, huskiness." OED says the Scottish -r- is a lingual trill, not a true burr.
"of or pertaining to the study of language," 1824, from German linguistisch (1807); see linguist + -ic. The use of linguistic to mean "of or pertaining to language or languages" (1847) is "hardly justifiable etymologically," according to OED, but "has arisen because lingual suggests irrelevant associations." Related: Linguistical; linguistically.
To the science which may be formed by comparing languages, the term Linguistic has been applied by some German authors. It is not, however, generally adopted, and is liable to some objections. ["Biblical Repository," vol. vii, no. 21, Jan. 1836]