Noun = Adverb(Potentially relevant link)
The 1913 edition of Webster's Unabridged Dictionary has this to say about 'Sufficience':
Suf*fi"cience (?), n.And this on 'Sufficiently':
Suf*fi"cient*ly, adv.Last I checked, nouns and adjectives were rarely synonyms.
To a sufficient degree; to a degree that answers the purpose, or gives content; enough; as, we are sufficiently supplied with food; a man sufficiently qualified for the discharge of his official duties.