atonic vs tonic

atonic is not a noun while tonic is a noun.

Word	Noun	Adjective	Verb	Adverb
atonic	No	Yes	No	No
tonic	Yes	Yes	No	No

atonic (noun)	tonic (noun)
	a medicine that strengthens and invigorates
	(music) the first note of a diatonic scale
	a sweet drink containing carbonated water and flavoring
	lime- or lemon-flavored carbonated water containing quinine

atonic (adjective)	tonic (adjective)
(used of syllables) carrying no stress	(used of syllables) bearing the principle stress, usually accompanied by a change in pitch
characterized by a lack of tonus	employing variations in pitch to distinguish meanings of otherwise similar words
	of or relating to or producing normal tone or tonus in muscles or tissue
	imparting vitality and energy
	relating to or being the keynote of a major or minor scale