Mid 17th century; earliest use found in Owen Felltham (?1602–1668), essayist and poet. From discoursive + -ness, perhaps originally as an alteration of discursiveness.
Definition of discoursiveness in US English:
discoursiveness
noundɪˈskɔːsɪvnɪs
The quality of being discoursive.
Origin
Mid 17th century; earliest use found in Owen Felltham (?1602–1668), essayist and poet. From discoursive + -ness, perhaps originally as an alteration of discursiveness.