Tending to make dull, blunt, or cause mental sluggishness; having a dulling or stupefying effect.
From hebetate + -ive, an adjectival suffix meaning 'having the quality of' or 'tending to.' This follows the same pattern as 'creative' from 'create' or 'meditative' from 'meditate.'
This adjective was used by 17th-century physicians to describe substances or conditions that had a dulling effect—like saying 'a hebetative drink' instead of 'a drink that makes you drowsy.'
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