non-synonymous
/ˌnɒnsɪˈnɒnɪməs/adjective
1Of two or more words, expressions, etc.: not having the same meaning.
2 Genetics. 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.