The Collaborative International Dictionary of English v.0.48:

Participial \Par`ti*cip"i*al\, a. [L. participialis: cf. E.
   participal. See Participle.]
   Having, or partaking of, the nature and use of a participle;
   formed from a participle; as, a participial noun. --Lowth.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Participial \Par`ti*cip"i*al\, n.
   A participial word.
   [1913 Webster]

WordNet (r) 3.0 (2006):

participial
    adj 1: of or relating to or consisting of participles;
           "participial inflections"
    n 1: a non-finite form of the verb; in English it is used
         adjectivally and to form compound tenses [syn:
         participle, participial]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "participial":
   adjectival, adverbial, attributive, conjunctive, copulative,
   correct, formal, functional, glossematic, grammatic, intransitive,
   linking, nominal, postpositional, prepositional, pronominal,
   structural, substantive, syntactic, tagmemic, transitive, verbal