A single word for a person who can speak many languages [duplicate]
Bi-glot is wrong, because you’re used the Latin prefix on the Greek suffix.
It should be diglot (also occasionally spelled di-glott in the 19th century), which the OED reports is a noun and an adjective meaning:
Using or containing two languages, bilingual; expressed or written in two languages; also as sb. A diglot book or version (cf. polyglot).
There is also a corresponding triglot for three.
Most diglots and triglots are Bibles, not people.
Wikipedia opines that polyglot is in fact a valid word in these circumstances, and for a speaker of many languages there is the word hyperpolyglot. It also says that for two languages or three languages, bilingual and trilingual do “fit the bill”. Multilingual fits too, although I think I would prefer to reserve that for more than three languages since there is a word trilingual.
However, -lingual is an adjectival form and you would have to describe someone as being bilingual or a bilingual person. Bilinguist doesn’t really work, and nor does diglot (you would need the Greek di- prefix to use with -glot).
One might coin the words oligoglot or paucilinguist for someone who can speak a few languages, but I don’t think either will catch on.
So if you don't want to use bilingual then you are left with polyglot and multilingual.
"Trilingual": adj. (of a person) speaking three languages fluently (Oxford Dictionary of English).
Merriam-Webster provides a similar definition for "trilingual":
adj. familiar with or able to use three languages