monolingual

/M AA0 N AH0 L IH1 NG G W AH0 L/
noun
  1. 1

    A person who knows or uses only a single language; a monoglot

adjective
  1. 1

    Knowing or using a single language; written or spoken in a single language.

Source: https://en.wiktionary.org/wiki/monolingual