ADVERBIALLY
adverbially
(adverb) as an adverb; “the prepositional phrase here is used adverbially”
Source: WordNet® 3.1
Etymology
Adverb
adverbially (not comparable)
As, or in the manner of, an adverb.
Source: Wiktionary
Ad*ver"bi*al*ly, adv.
Definition: In the manner of an adverb.
ADVERBIAL
Ad*ver"bi*al, a. Etym: [L. adverbialis: cf. F. adverbial.]
Definition: Of or pertaining to an adverb; of the nature of an adverb; as,
an adverbial phrase or form.
Source: Webster’s Unabridged Dictionary 1913 Edition