weak form

weak form (svak form): a pronunciation of a word that entails some degree of phonological reduction. Only a relatively small number of words have weak forms, and they are all function words. The phonological reduction can consist in reducing the number of phonemes in the word (e.g. his: /hIz/ has a weak form /iz/) and/or in using one of the weak vowels (i, u, and schwa) instead of the full vowels. The general rule for using weak forms is as follows: The weak form of a word is used whenever the word is unstressed, unless the word occurs finally in a tone unit.