diagonic,a.rare.|daɪəˈgɒnɪk| [ad. L. diagōnicus (Vitruvius), a. Gr. διαγωνικός: see diagonal and -ic.] = diagonal. 1592R. D. Hypnerotomachia 7 Meeting together over the Diagonike line.1881J. Milne in Nature 8 Dec. 126 This particular earthquake..might therefore be called a transverse or diagonic shock.