apothecial,a.|æpəʊˈθiːʃɪəl| [f. apothecium + -al.] Of or pertaining to an apothecium. 1882J. M. Crombie in Encycl.Brit. XIV. 559 Apothecial reactions for the most part take place either externally on the epithecium or internally on the hymenial gelatin.