\De*vo"cal*ize\, v. t.
To make toneless; to deprive of vowel quality. --
{De*vo`cal*i*za"tion}, n.
      If we take a high vowel, such as (i) [= nearly i of
      bit], and devocalize it, we obtain a hiss which is
      quite distinct enough to stand for a weak (jh). --H.
                                               Sweet.