weak vowel merger

noun2

1. •
   A phenomenon found in English pronunciation where the phonemes /ə/ (schwa) and /ɪ/ (the near-close near-front unrounded vowel) are not distinguished from eachother when unstressed, with the resulting ambiguous phoneme represented in the International Phonetic Alphabet as /ɨ/ (a close central rounded vowel).
2. •
   An instance of this merger in a specific usage or pronunciation of a word or phrase.

   • Because many terms in various dialects of English undergo weak vowel mergers, words ending with /ə/ and /ɪ/ which usually do not rhyme could be considered to with eachother.