:Rhythmic clipping:

The reduction of the duration of a vowel, sonorant consonant, or sequence of sonorant sounds occasioned by rhythmic factors. An example is the difference in the duration of vowel in the syllable mat when it occurs in a foot without accompanying unstressed syllables, compared to, say, its duration when it occurs with following unstressed syllables, as in a word such as matador. Informal measurements indicate that the duration of the vowel in the latter is less than 50% of the duration of the vowel in the former.