> as lemmas

1868 N. Amer. Rev. July 353 We are not satisfied with the defined relations, internal or external, of the group of vowels of ‘mixed’ position (made by action both of front and back of tongue), variations, sometimes trivial or imaginary, of the ‘neutral’ vowel, as it has been commonly styled.

1878 Mind 3 393 I may explain that in this notation, while ú, í, are the long Continental a and i, unaccented a is not the short Continental a, but the obscure or neutral vowel (Urvocal) heard in English ‘at,’ ‘that,’ ‘but,’ when not emphatic; when strongly given, it becomes the full sound of u in emphasised ‘but’.

1891 L. Soames Introd. Phonetics i. iii. 50 The obscure vowel ‘a’ in attend.., sometimes called the natural or the neutral vowel.

1948 J. R. Firth Papers in Ling. 1934–51 (1957) ix. 131 The weak, neutral, or ‘minimal’ vowel... The term neutral suits it in English, since it is in fact neutral to the phonematic system of vowels in southern English.

1972 R. A. Palmatier Gloss. Eng. Transformational Gram. 103 Neutral vowel,..the mid central vowel ‘schwa’ [ə]—or the high central vowel ‘barred i’ [ɨ]—to which insufficiently stressed vowels are reduced.