onomatopoeic vs onomatopoeical

onomatopoeic and onomatopoeical both are adjectives.

Word	Noun	Adjective	Verb	Adverb
onomatopoeic	No	Yes	No	No
onomatopoeical	No	Yes	No	No

As adjectives, onomatopoeic and onomatopoeical are synonyms defined as:

onomatopoeic and onomatopoeical: (of words) formed in imitation of a natural sound

Other synonyms of onomatopoeic include echoic, imitative, onomatopoetic.

onomatopoeic (adjective)	onomatopoeical (adjective)
(of words) formed in imitation of a natural sound	(of words) formed in imitation of a natural sound
of or relating to or characterized by onomatopoeia