The Greek adjective Hebraïkos (Ἑβραϊκός) means 'Hebrew' — pertaining to the Hebrew language, script, or culture. It appears in Luke 23:38 (in some manuscripts) and Revelation 9:11, 16:16 describing inscriptions or names in Hebrew as distinct from Latin or Greek.
The appearance of Hebrew language designations in the New Testament is theologically significant. Even in the Greek-dominated Roman world, Hebrew remained the sacred language of covenant and Scripture. Revelation 9:11 gives both the Hebrew and Greek name for the angel of the Abyss (Abaddon/Apollyon), and Revelation 16:16 names Armageddon by its Hebrew designation. John's use of Hebrew names at pivotal eschatological moments signals that the final events of history are deeply rooted in the covenantal history of Israel. The Hebrew language is not merely ethnic heritage — it is the language through which God first spoke His covenant to His people.