If bilingual means you know two languages, and trilingual means you know three, what would be the proper term for knowing four, five or even six languages?
- person having a speaking, reading, or writing knowledge of several languages.
A multilingual person, in a broad definition, is one who can communicate in more than one language, be it actively (through speaking, writing, or signing) or passively (through listening, reading, or perceiving). More specifically, the terms bilingual and trilingual are used to describe comparable situations in which two or three languages are involved. A multilingual person is generally referred to as a polyglot. Poly (Greek: πολύς) means "many", glot (Greek: γλώσσα) means "language".
From Wikipedia, the online encyclopedia: http://en.wikipedia.org/wiki/Multilingualism#Multilingual_individuals
Able to speak four languages.