two-tongued

adjective3

1. •
   Having two tongues; double-tongued.
2. •
   Deceitful; lying; two-faced.
3. •
   (rare) Possessing the ability to speak two languages; synonym of bilingual.

   • Thomas had used "the bilingual sea" in "Quite Early One Morning" (1945), so that "two-tongued" was a product of a natural piece of wordplay. — 1963