Wordnet 3.0
NOUN (1)
1.
a word or group of words function as an adverb;
ADJECTIVE (1)
1.
of or relating to or functioning as an adverb;
- Example: "adverbial syntax"
The Collaborative International Dictionary of English v.0.48:
Adverbial \Ad*ver"bi*al\, a. [L. adverbialis: cf. F. adverbial.]
Of or pertaining to an adverb; of the nature of an adverb;
as, an adverbial phrase or form.
[1913 Webster]
WordNet (r) 3.0 (2006):
adverbial
adj 1: of or relating to or functioning as an adverb; "adverbial
syntax"
n 1: a word or group of words function as an adverb