Learn English – Proper term for knowing four or more languages

Biliterate is defined as:

1. (adj) able to read and write in two languages.
2. (noun) a person who is biliterate.

However, it appears that multiliteracy has morphed into a whole other meaning having to do with multimodal ways of communicating.

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 19^th 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.