noun

• (phonology) Any of two or more alternative pronunciations for a phoneme.
  "In some languages, [ʋ] is an allophone of /v/."
• A person whose mother tongue is one other than that spoken by the majority.
  "However, “the languages used by STM staff during customer interactions are French and English,” the transit authority said. “Indeed, during phone calls or emails, STM employees speak English with anglophone or allophone customers who do not speak French.”"

adj

• (Canada) Of or relating to those whose mother tongue is neither English, French, nor (sometimes) an indigenous language of Canada.
  "In every case the allophone population is vastly larger than the proportion of francophones, which ranges from 4.2 percent […] from other parts of Canada more than international immigration from abroad: despite a growing allophone presence, […]"