Assonance is a resemblance in the sounds of words/syllables either between their vowels or between their consonants. However, assonance between consonants is generally called consonance in American usage. The two types are often combined, as between the words six and switch, in which the vowels are identical, and the consonants are similar but not completely identical. If there is repetition of the same vowel or some similar vowels in literary work, especially in stressed syllables, this may be termed "vowel harmony" in poetry.