I. -ˈri-fik adjective
Etymology: probably from French soporifique, from Latin sopor deep sleep; akin to Latin somnus sleep — more at somnolent
Date: 1665
1.
a. : causing or tending to cause sleep
soporific drugs
b. : tending to dull awareness or alertness
2. : of, relating to, or marked by sleepiness or lethargy
II. noun
Date: circa 1727
: a soporific agent ; specifically : hypnotic 1