the GNU version of the Collaborative International Dictionary of English
adj. Causing sleep; somniferous.
The Century Dictionary and Cyclopedia
Causing sleep: tending to induce sleep; somniferous; soporific.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. sleep inducing
Word Usage
"Here, weariness and the somnific effects of a generous heat, speedily found him stretched at full length towards the fire, snoring away at a sound rate, the subject of their combined influence."