The sublingua (`under-tongue`) is a muscular secondary tongue found below the primary tongue in prosimian primates, which includes lemurs, lorisoids, and tarsiers. Although it is most fully developed in prosimian primates, similar structures can be found in some other mammals, such as marsupials, treeshrews, and colugos. This `second tongue` l...
• (n.) A process or fold below the tongue in some animals.
Sub·lin'gua noun ; plural Sublinguæ . [ New Latin ] (Anat.) A process or fold below the tongue in some animals. 
sublingua In anatomy, a process or fold below the tongue in some animals.