apocynaceous,a.Bot.|əˌpɒsɪˈneɪʃəs| [f.mod.L. Apocynāceæ: see next and -aceous.] Of or belonging to the family Apocynaceæ, or ‘Dog-banes,’ including the Periwinkles and Oleanders. 1883Knowl. 7 Sept. 154/2 A new apocynaceous plant, which..yields abundant supplies of pure caoutchouc.