Misenunciate

The training is not primarily intended for children who merely mispronounce or misenunciate or express themselves inaptly, unidiomatically and incorrectly for reasons other than defects of speech.

Source: wiktionary

What common words are usually misenunciated because of failure to open the mouth properly?

Source: wiktionary

In the method recommended here, when the sounds in nonsense combinations are larned no act of attention is required to repeat them, and when once a sequence of sounds which are used as part of a word is easily enunciated it slips into the formerly misenunciated word and makes it correct without any conscious effort on the part of the pupil.

Source: wiktionary

It has been my experience that South Africans misenunciate more than half of these vowel sounds.

Source: wiktionary