The Collaborative International Dictionary of English v.0.48:

Admissive \Ad*mis"sive\, a.
   Implying an admission; tending to admit. [R.] --Lamb.
   [1913 Webster]

WordNet (r) 3.0 (2006):

admissive
    adj 1: characterized by or allowing admission; "an Elizabethan
           tragedy admissive of comic scenes"

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "admissive":
   admissible, admissory, allowing, confessional, consenting,
   hospitable, imbibitory, indulgent, ingestive, intromissive,
   intromittent, invitatory, inviting, lax, lenient, nonprohibitive,
   open, open-minded, permissive, permitting, persuadable,
   persuasible, receivable, receptible, receptive, recipient,
   suffering, tolerant, tolerating, unprohibitive, welcoming