different between nonblack vs nonback

English

non- +? black

nonblack (not comparable)

nonblack (plural nonblacks)

non- +? back

nonback (not comparable)

(phonetics) Not back; not produced at the back of the mouth.
- 1982, John J McCarthy, Formal problems in semitic phonology and morphology:
  Therefore these facts are doubly anomalous, since they have not only gemination after a nonback vowel but also after a vowel that is stressed.
(medicine) Not of or pertaining to the back (rear side of the body).
- 1973, Lawrence W Friedmann, Lawrence Galton, Freedom From Backaches:
  As we have noted, back pain may stem from many nonback conditions, including peptic ulcer, prostate disease, kidney disease, retroverted uterus...

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