un·ci·al / ˈənshəl; -sēəl/ • adj. 1. of or written in a majuscule script with rounded unjoined letters that is found in European manuscripts of the 4th–8th centuries and from which modern capital letters are derived. 2. rare of or relating to an inch or an ounce.• n. an uncial letter or script. ∎  a manuscript in uncial script.

uncial of or written in a majuscule script with rounded unjoined letters which is found in European manuscripts of the 4th–8th centuries and from which modern capital letters are derived. The term is recorded from the late 17th century and comes from late Latin unciales littera ‘uncial letters’, the original application of which is unclear. (One explanation has been that the phrase stands for ‘letters of an inch long’ from Latin uncia ‘inch’; the emendations initiales ‘initial’ and uncinales ‘hooked, bent’ have also been suggested.)

uncial
A. pert. to an inch or an ounce XVII;

B. (palaeogr.) after late L. unciales litteræ, having the large rounded forms characteristic of early Gr. and L. manuscripts XVIII. — L. unciālis, f. uncia INCH1, OUNCE1; see -AL1. In sense B the orig. application is obscure.