R-colored vowel

In phonetics, an r-colored vowel or rhotacized vowel is a vowel either with the tip or blade of the tongue turned up during at least part of the articulation of the vowel (a retroflex articulation) or with the the tip of the tongue down and the back of the tongue bunched. Both articulations produce basically the same auditory effect, a lowering of the third formant. In English, only rhotic accents like General American contain r-colored vowels. They are cross-linguistically rather rare, but occur also in some varieties of Mandarin Chinese.