Pretty much all there in the title—is there an official scientific term for a “forked tongue,” like snakes have?
Why do I want to know? Simple: I need to name an airship. Duh.
I found the term diglossia although it seems to be uncommon as a medical term and is used more commonly in linguistics (where it has a different meaning).
The term that immediately came to mind, and appears to be the more common term for what you are thinking of, is bifid tongue.
Lingua bifurcata?
Hirundo82 has the right word, bifid. The definition on his link suggests that the phrase “bifid tongue” refers to a defect. The word bifid simply implies forkedness, not a defect, and I have seen “bifid tongue” used in scientific papers and diagnostic keys to describe the tongues of snakes and some lizards for whom a bifid tongue is not a defect.