monster vs teras

monster and teras both are nouns.

Word	Noun	Adjective	Verb	Adverb
monster	Yes	No	No	No
teras	Yes	No	No	No

As nouns, monster and teras are synonyms defined as:

monster and teras: (medicine) a grossly malformed and usually nonviable fetus

monster (noun)	teras (noun)
(medicine) a grossly malformed and usually nonviable fetus	(medicine) a grossly malformed and usually nonviable fetus
a cruel wicked and inhuman person
a person or animal that is markedly unusual or deformed
an imaginary creature usually having various human and animal parts
someone that is abnormally large and powerful