Origin of the name Stefan: From the Latin Stephanus, which is from the Greek Stephanos, a name derived from stephanos (a crown, a garland). The name is borne in the Bible by St Stephen, one of the seven chosen to assist the apostles, and the first Christian martyr.
Meaning: Crown; wreath. Variant of Stephen. Origin: Gaelic
The old Gaelic name used by the Sullivan family in Ireland was O Suileabhain, which is partially derived from the word "suil," which means "eye." The surname probably means either one-eyed or hawk-eyed.