LINGUAL.
1. Relating to the TONGUE, as with a lingual protrusion lisp, a lisp caused by the tongue coming forward too far.

2. In PHONETICS, formed by (especially the tip of) the tongue, as with the consonants /d, t, n/; a lingual sound.

3. Relating to LANGUAGES: lingual skills. The simple adjective is rare in this sense, but the combining form -lingual is common, as in bi-, tri-, and quadrilingual able to use two, three, and four languages respectively. There are two terms for ‘able to use (only) one language’: the commoner monolingual (a hybrid form using GREEK-derived mono- sole) and the etymologically more consistent unilingual (using LATIN-derived un- one). The latter is common in CanE, under the influence of FRENCH unilingue. Compare -GLOT. See BILINGUALISM, MULTILINGUALISM.

lin·gual / ˈlinggwəl/ • adj. technical 1. of or relating to the tongue. ∎ Phonet. (of a sound) formed by the tongue. ∎ Anat. near or on the side toward the tongue.2. of or relating to speech or language: his demonstrations of lingual dexterity.• n. Phonet. a lingual sound.DERIVATIVES: lin·gual·ly adv.

lingual (ling-wăl) adj. relating to, situated close to, or resembling the tongue (lingua).

lingual Of the tongue.