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Webster 1913 Edition

Adj.

Noun.

[Cf. F.

stupéfactif

, LL.

stupefactivus

Same as

[Written also

stupifactive

Adj.

Causing insensibility; deadening or blunting the sense of felling or understanding; narcotic.

Opium hath a stupefactive part.

stupefactive ‎(comparative more stupefactive, superlative most stupefactive)

Inducing stupor; making drowsy; stupefacient.
- 1841, Benjamin Parsons, The wine question settled (page 7)
  Opium and laudanum, which is a preparation of opium, are both stimulating and stupefactive.