Adjective
open-mid (not comparable)
(phonetics, of a vowel) pronounced with the tongue in a position approximately one-third of the way between an open and a close vowel
In some languages, like Spanish and Romanian, the phonemic status and difference between open-mid and close-mid vowels was lost. Source: Internet
The other vowels are 'auditorily equidistant' between these three 'corner vowels', at four degrees of aperture or 'height': close (high tongue position), close-mid, open-mid, and open (low tongue position). Source: Internet