The Collaborative International Dictionary
Participative
Participative \Par*tic"i*pa*tive\ (p[aum]r*t[i^]s"[i^]*p[asl]*t[i^]v), a. [Cf. F. participatif.] Capable of participating.
Douglas Harper's Etymology Dictionary
participative
1650s, from participate + -ive.
Wiktionary
participative
a. That participates, or is capable of participating