Definition of non-synonymous in English:

non-synonymous

Pronunciation /ˌnɒnsɪˈnɒnɪməs/

adjective

  • 1Of two or more words, expressions, etc.: not having the same meaning.

  • 2Genetics
    Designating a point mutation (base-pair change) in a codon that results in a change in the amino acid produced during translation.

Origin

1950s; earliest use found in The Philosophical Review. From non- + synonymous.