A drug or other substance that induces sleep; a hypnotic.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "soporific" in a sentence
"There is a misunderstanding about the meaning of the word soporific and when Thompson explains it to McDonald they both enjoy a laugh, at themselves mostly, they let go a little, and it is one of the most human and intimate moments in the film up until that point."
"Could anyone ever consider terrific a delivery best called soporific?"
"It may be remembered that Archibald, in what we may term his soporific period, had manifested a strong, although entirely irrational, repugnance to this east chamber."