What is Meant by multilingual.

Definition:
The ability of an individual speaker or a community of speakers to use multiple languages. Contrast with monolingualism, the ability to use only one language.
A person who can speak multiple languages is known as a polyglot or a multilingual.

Examples and Observations:

• "We estimate that most of the human language users in the world speak more than one language, i.e. they are at least bilingual. In quantitative terms, then, monolingualism may be the exception and multilingualism the norm. . . .
  
  "[I]t is a reasonable assumption that the marginal role research on multingualism has played within linguistics until some decades ago is a result of the monolingual bias of (particularly) European thinking about language which came into being during a phase of European history in which the nation states defined themselves not in the least by the one (standard) language which was chosen to be the symbolic expression of their unity. . . .
  
  "[I]t can be argued that what we perceive as the problems surrounding multilingualism today are to a large degree a consequence of the monolingualism demanded, fostered and cherished by the nation states in Europe and their knock-offs around the world."
  (Peter Auer and Li Wei, "Introduction: Multilingualism As a Problem? Monolingualism As a Problem?" Handbook of Multilingualism and Multilingual Communication. Mouton de Gruyter, 2007)

• Bilingualism and Multilingualism
  "Current research . . . begins by emphasizing the quantitative distinction between multilingualism and bilingualism and the greater complexity and diversity of the factors involved in acquisition and use where more than two languages are involved (Cenoz 2000; Hoffmann 2001a; Herdina and Jessner 2002). Thus, it is pointed out that not only do multilinguals have larger overall linguistic repertoires, but the range of the language situations in which multilinguals can participate, making appropriate language choices, is more extensive. Herdina & Jessner (2000b:93) refer to this capacity as 'the multilingual art of balancing communicative requirements with language resources.' This wider ability associated with the acquisition of more than two languages has also been argued to distinguish multilinguals in qualitative terms. One . . . qualitative distinction seems to lie in the area of strategies. Kemp (2007), for example, reports that multilingual learners' learning strategies differ from those of monolingual students learning their first foreign language."
  (Larissa Aronin and David Singleton, Multilingualism. John Benjamins, 2012)