High Day

Is found in Ge 29:7 as a rendering of the Hebrew yom agadhol, literally, "great day." The Hebrew means the day at its height, broad daylight as contrasted with the time for getting the cattle to their sheds for the night (compare French grand jour). In Joh 19:31, "highday" renders megale hemera, literally, "great day," and refers to the Passover Sabbath--and therefore a Sabbath of special sanctity.

⇒See the definition of high in the KJV Dictionary