trillion vs zillion

trillion and zillion both are nouns.

Word	Noun	Adjective	Verb	Adverb
trillion	Yes	Yes	No	No
zillion	Yes	Yes	No	No

As nouns, trillion and zillion are synonyms defined as:

trillion and zillion: a very large indefinite number (usually hyperbole)

Other synonyms of trillion include bazillion, billion, gazillion, jillion, million.

trillion (noun)	zillion (noun)
the number that is represented as a one followed by 12 zeros	a very large indefinite number (usually hyperbole)
the number that is represented as a one followed by 18 zeros in the UK
a very large indefinite number (usually hyperbole)

trillion (adjective)	zillion (adjective)
one million million in the United States	very large indeterminate number
one quintillion in Great Britain