Real Dictionary

uncial in American English
an uncial letter
designating or of a form of large, rounded letter used in the script of Greek and Latin manuscripts between a. d. 300 and 900
adjective: designating, written in, or pertaining to a form of majuscule writing having a curved or rounded shape and used chiefly in Greek and Latin manuscripts from about the 3rd to the 9th century a.d.

uncial in British English
adjective: of, relating to, or written in majuscule letters, as used in Greek and Latin manuscripts of the third to ninth centuries, that resemble modern capitals, but are characterized by much greater curvature and inclination and general inequality of height
noun: an uncial letter or manuscript