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definitions

dis-

1
  1. a Latin prefix meaning “apart,” “asunder,” “away,” “utterly,” or having a privative, negative, or reversing force (see de-, un-2); used freely, especially with these latter senses, as an English formative: disability; disaffirm; disbar; disbelief; discontent; dishearten; dislike; disown.
Also di-.

Origin of dis-

1
< Latin (akin to bis, Greek dís twice); before f, dif-; before some consonants, di-; often replacing obsolete des- < Old French

dis-

2
  1. variant of di-1 before s: dissyllable.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for dis-

dis-

1
prefix
  1. indicating reversaldisconnect; disembark
  2. indicating negation, lack, or deprivationdissimilar; distrust; disgrace
  3. indicating removal or releasedisembowel; disburden
  4. expressing intensive forcedissever

Word Origin for dis-

from Latin dis- apart; in some cases, via Old French des-. In compound words of Latin origin, dis- becomes dif- before f and di- before some consonants

dis-

2
combining form
  1. variant of di- 1 dissyllable
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 dis-

(assimilated as dif- before -f-, to di- before most voiced consonants), word-forming element meaning 1. "lack of, not" (e.g. dishonest); 2. "do the opposite of" (e.g. disallow); 3. "apart, away" (e.g. discard), from Old French des- or directly from Latin dis- "apart, in a different direction, between," figuratively "not, un-," also "exceedingly, utterly," from PIE *dis- "apart, asunder" (cf. Old English te-, Old Saxon ti-, Old High German ze-, German zer-).

The PIE root is a secondary form of *dwis- and thus is related to Latin bis "twice" (originally *dvis) and to duo, on notion of "two ways, in twain."

In classical Latin, dis- paralelled de- and had much the same meaning, but in Late Latin dis- came to be the favored form and this passed into Old French as des-, the form used for new compound words formed in Old French, where it increasingly had a privative sense ("not").

In English, many of these words eventually were altered back to dis-, while in French many have been altered back to de-. The usual confusion prevails.

Online Etymology Dictionary, © 2010 Douglas Harper
dis- in Medicine

dis-

pref.
  1. Not:disjugate.
  2. Absence of; opposite of:disorientation.
  3. Undo; do the opposite of:dislocate.
  4. Deprive of; remove:dismember.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.