ethnic vs ethnical

ethnic is a noun but ethnical is not a noun.

Word	Noun	Adjective	Verb	Adverb
ethnic	Yes	Yes	No	No
ethnical	No	Yes	No	No

As adjectives, ethnic and ethnical are synonyms defined as:

ethnic and ethnical: denoting or deriving from or distinctive of the ways of living built up by a group of people

Other synonyms of ethnic include cultural.

ethnic (noun)	ethnical (noun)
a person who is a member of an ethnic group

ethnic (adjective)	ethnical (adjective)
not acknowledging the God of Christianity and Judaism and Islam	denoting or deriving from or distinctive of the ways of living built up by a group of people
denoting or deriving from or distinctive of the ways of living built up by a group of people