diacritical adjective 2noun 1forms 3 adjective2 •Of, pertaining to, or serving as a diacritic.The reduplicated forms and the fineness of the diacritical strokes, render his book troublesome to the reader — 1869 •Capable of distinguishing or of making a distinction. noun1 •Synonym of diacritical mark (adnoun equivalent). formsdiacriticals · more diacritical · most diacritical