thurd (shelishi; tritos): Isa 19:24, "In that day shall Israel be the third with Egypt and with Assyria," etc., brings out very distinctly the universal and missionary character of Isaiah's prophecies and of Israel's destiny (compare Eze 16:63; and see G. A. Smith, Isaiah, II, 275, 278; Watkinson, Th. Blind Spot 21 ff).
⇒See the definition of third in the KJV Dictionary
For "third hour," "third month," "third year," see CALENDAR; DAY; TIME.