MONOLINGUAL
monolingual
(adjective) using or knowing only one language; “monolingual speakers”; “a monolingual dictionary”
monolingual
(noun) a person who knows only one language
Source: WordNet® 3.1
Etymology
Adjective
monolingual (comparative more monolingual, superlative most monolingual)
Knowing or using a single language; written or spoken in a single language.
Synonym: unilingual
Antonyms: multilingual, plurilingual
Noun
monolingual (plural monolinguals)
a person who knows or uses only a single language; a monoglot
Source: Wiktionary