A homovocalic (HV) is a word with one or more vowels, in which all the vowels are the same. ANAGRAM is a homovocalic. Originally christened 'vocalic invariants' by Dmitri Borgmann in Language on Vacation (LonV), they have been called monovocalics, sometimes univocalics, in Word Ways.
"A Homovocalic Survey,"
Word Ways: Vol. 38
, Article 16.
Available at: http://digitalcommons.butler.edu/wordways/vol38/iss2/16