Is it ensure, insure, or assure?
1530s, from Medieval Latin tragonia, from Byzantine Greek tarchon, from Arabic tarkhon, from a non-Arabic source, perhaps Greek drakon (from drakontion "dragonwort"). Eastern European plant of the wormwood genus (Artemisia Dracunculus), whose aromatic leaves were used for flavoring (especially vinegar). Cf. Spanish taragona, Italian targone, French estragon.