From saraph; burning, i.e. (figuratively) poisonous (serpent); specifically, a saraph or symbolical creature (from their copper color) -- fiery (serpent), seraph.
see HEBREW saraph
H8314. saraph
I. שָׂרָף noun masculineIsaiah 14:29 a serpent, usually venomous (possibly from above v, from burning effect of poison); — absolute ׳שׂ Numbers 21:8 (J E; on Arabic parallels see JacobArabic Dichter ii. 93, iv. 10 f.), apposition שׂ ׳נָחָשׁ Deuteronomy 8:15, plural הַשְּׂרָפִים הַנְּחָשִׁים Numbers 21:6; a flying serpent, or dragon, מְעוֺפֵף שָׂרָף Isaiah 14:29; 30:6.
II. [שָׂרָף] noun masculineIsaiah 6:2 plural שְׂרָפִים seraphim (probably akin to I. ׳שׂ, as beings originally mythically conceived with serpents' bodies (serpent-deities, compare 14:29; 30:6), or (CheComm.) personified of lightning, compare arts. SERAPHIM, StrachanHast. DB CheEncy. Bib.; Di Marti and others compare also Egyptian guardian-griffins, called Šerref; see also כְּרוּב; on Assyrian Šarrapu (-bu), epithet of god Nergal, connected by DlWB with √ שָׂרַף, see שָׁרָב, ZimKAT 3. 415); — in OT. majestic beings with six wings, and human hands and voices, attendant upon ׳י 6:2, 6.