de-

1.
a prefix occurring in loanwords from Latin (decide); also used to indicate privation, removal, and separation (dehumidify), negation (demerit; derange), descent (degrade; deduce), reversal (detract), intensity (decompound).
Compare di-2 , dis-1 .
Origin
Middle English < Latin dē-, prefixal use of dē (preposition) from, away from, of, out of; in some words, < French < Latin dē- or dis- dis-1
British Dictionary definitions for de-

de-

prefix
1.
removal of or from something specified: deforest, dethrone
2.
reversal of something: decode, decompose, desegregate
3.
departure from: decamp
Word Origin
from Latin, from dē (prep) from, away from, out of, etc. In compound words of Latin origin, de- also means away, away from (decease); down (degrade); reversal (detect); removal (defoliate); and is used intensively (devote) and pejoratively (detest)
Word Origin and History for de-

active word-forming element in English and in many words inherited from French and Latin, from Latin de "down, down from, from, off; concerning" (see de), also used as a prefix in Latin usually meaning "down, off, away, from among, down from," but also "down to the bottom, totally" hence "completely" (intensive or completive), which is its sense in many English words. As a Latin prefix it also had the function of undoing or reversing a verb's action, and hence it came to be used as a pure privative -- "not, do the opposite of, undo" -- which is its primary function as a living prefix in English, as in defrost (1895), defuse (1943), etc. Cf. also dis-.

de- in Medicine

de- pref.

  1. Do or make the opposite of; reverse: decomposition.

  2. Remove or remove from: deoxygenation.

  3. Reduce; degrade: decholesterolization.