Gliding towards a high(er) vowel.

Gliding towards the central vowel sound/ə/, as in words like air, here, and poor, and in U.S. regional pronunciations like wood [wʊəd], bell [bɛəl]…

Of a sound: consisting of or involving an off-glide (see off-glide, n.).

of the nature of or relating to an on-glide.