phobos (Greek #5401)
alarm or fright
KJV usage: be afraid, + exceedingly, fear, terror.
Pronounce: fob'-os
Origin: from a primary φέβομαι (to be put in fear)
megas (Greek #3173)
big (literally or figuratively, in a very wide application)
KJV usage: (+ fear) exceedingly, great(-est), high, large, loud, mighty, + (be) sore (afraid), strong, X to years.
Pronounce: meg'-as
Origin: (including the prolonged forms, feminine μεγάλη, plural μεγάλοι, etc.; compare also 3176, 3187)