a combining form meaning “sleep”, used in the formation of compound words: somnifacient.

Also especially before a vowel, somn-. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for somni-


before a vowel somn-

combining form


Word Origin for somni-

from Latin somnus
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for somni-

before vowels somn-, word-forming element meaning "sleep," from comb. form of Latin somnus (see Somnus).

Online Etymology Dictionary, © 2010 Douglas Harper

somni- in Medicine



The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.