Apex
Apex a stitched cap, somewhat resembling a helmet, with the addition of a little stick fixed on the top, and wound about with white wool, properly belonging to the ancient Flamen (q.v.)'.
The word is also used by Jerome to express a small hair-stroke, with which the Jews embellish the top of some of the Hebrew characters, placing it over them in the shape of a crown. These are used especially in the books read in the synagogues, and in the Mezuzzoth (q.v.).