The Big Old Man of the Sea

The Manx word for giant is foawr, in which a vowel-flanked “m” has been spirited away, as shown by the mordern Irish spelling, fomhar ... I have been in the habit of explaining the word as submarini but no more are they invariably connected with the sea. So another etymoloygy recommmends itself, one which comes from Dr. Whitley Stokes, and makes the mor in fomori to be of the same origin as the mare in the English nightmare ...

-- John Rhys, “Celtic Folklore”

(So II wonder if the dolphin-rider emblem on the my father’s family crest to that of a naked giant riding on the back of a whale, or Manannan astride his grey horse “Wave Sweeper” )