Definition of non-distinctive in US English:
non-distinctive
adjective
Not distinctive; (Linguistics) designating a feature of a spoken language whose replacement affects meaning.
Origin
Early 20th century; earliest use found in Daniel Jones (1881–1967), phonetician. From non- + distinctive.
Pronunciation
non-distinctive
/ˌnɒndɪˈstɪŋ(k)tɪv/