Leviathan

a transliterated Hebrew word (livyathan), meaning "twisted,"
"coiled." In Job 3:8, Revised Version, and marg. of Authorized
Version, it denotes the dragon which, according to Eastern
tradition, is an enemy of light; in 41:1 the crocodile is meant;
in Ps. 104:26 it "denotes any large animal that moves by
writhing or wriggling the body, the whale, the monsters of the
deep." This word is also used figuratively for a cruel enemy, as
some think "the Egyptian host, crushed by the divine power, and
cast on the shores of the Red Sea" (Ps. 74:14). As used in Isa.
27:1, "leviathan the piercing [R.V. 'swift'] serpent, even
leviathan that crooked [R.V. marg. 'winding'] serpent," the word
may probably denote the two empires, the Assyrian and the
Babylonian.