Definition from Wiktionary, the free dictionary
tughra (plural tughras)
- A calligraphic signature of an Ottoman sultan (and some other rulers to the present day) that was affixed to official documents, carved on his seal, and stamped on coins and inscribed on some stamps issued during his reign.
signature of an Ottoman sultan
- ^ "toughra." *OED 2nd edition. 1989. (online)