The Collaborative International Dictionary
Stupefactive
Stupefactive \Stu`pe*fac"tive\, a. & n. [Cf. F. stup['e]factif, LL. stupefactivus.] Same as Stupefacient. [Written also stupifactive.]
Wiktionary
stupefactive
a. Inducing stupor; making drowsy; stupefacient.