Thebaic /θɪˈbeɪ.ɪk/adjective 2noun 1forms 1 adjective2 •(no longer used, rare) Of or pertaining to opium.Thebaic extract, half a dram. — 1791 •(no longer used, rare) Theban; of or pertaining to Thebes, especially in the context of the Coptic scriptures.priests, monks, missionaries who, by way of this strange detour via Ireland, brought the spirit of Thebaic asceticism to Europe; […] — 1957 noun1 •(no longer used) An opium-based medication or tincture such as laudanum. formsThebaics