serpent vs ophidian

serpent and ophidian both are nouns.

Word	Noun	Adjective	Verb	Adverb
serpent	Yes	No	No	No
ophidian	Yes	No	No	No

As nouns, serpent and ophidian are synonyms defined as:

serpent and ophidian: limbless scaly elongate reptile; some are venomous

Other synonyms of serpent include snake.

serpent (noun)	ophidian (noun)
limbless scaly elongate reptile; some are venomous	limbless scaly elongate reptile; some are venomous
an obsolete bass cornet; resembles a snake
a firework that moves in serpentine manner when ignited