(1):

(n.) One of the sonant mutes /, /, / (b, d, g), in Greek, or of their equivalents in other languages, so named as intermediate between the tenues, /, /, / (p, t, k), and the aspiratae (aspirates) /, /, / (ph or f, th, ch). Also called middle mute, or medial, and sometimes soft mute.

(2):

(n.) pl. of Medium.

(3):

(pl.) of Medium