Synonyms for Decrease:

n.

crater, dip. cut back, halve, increase, rebate, shrivel, trim down, let up, top-slice. collapse, cutback, plunge. contraction (noun)
deflation, elision.
decrease (noun)
abbreviation, abridgement, compaction, compression, concentration, contraction, curtailment, decrement, deduction, deflation, depletion, diminish, diminution, erosion, fall, lessen, lessening, minify, reduction, shrinkage, truncation, Diminishment, drop off, step down.
depression (noun)
attenuation, debasement, depression, diminution, sinking.
diminishing, lessening (noun)
abatement, compression, contraction, cutback, depression, diminution, discount, loss, reduction, shrinkage.
event (noun)
lessening.
loss (noun)
attrition, debit, deprivation, dispossession, dissipation, dissolution, divestiture, exhaustion, expropriation, forfeiture, loss, penalty, privation, ruin, setback.
process (noun)
decrement.
shrinkage (noun)
abatement.
subtraction (noun)
deletion, depreciation, elision, lessening, lowering, subtraction.

v.

change (verb)
diminish, fall, lessen.
curtail (verb)
discontinue, fragment, minimize, reduce.
decrease (verb)
abate, abbreviate, abridge, compact, compress, concentrate, contract, curtail, decrement, deduct, deflate, deplete, die down, diminish, drain, dwindle, erode, lessen, lower, recede, shorten, shrink, subside, truncate.
depress (verb)
attenuate, debase, depress, sink.
diminish (verb)
bob, clip, condense, crop, cull, downgrade, lighten, nip, pare, prune, shave, shear, taper, trim, weed.
grow less or make less (verb)
abate, contract, curtail, depreciate, die down, diminish, drop, dwindle, lessen, lighten, lower, reduce, shrink, shrivel, sink, subside, drop off, let up.
lessening (verb)
abatement.
lose (verb)
dispossess, dissipate, dissolve, divest, drop, exhaust, forfeit, lose, misplace.
subtract (verb)
cut, delete, depreciate, discount, dock, elide, subtract.

Other synonyms:

crater, cutback, plunge, shrivel, trim down, top-slice. collapse, dip. halve, rebate. contract
lose.
curtail
minify.
cut short
clip.
deteriorate
sink.
drop-off
drop off.
economize
cut back.
lessen
lessening.
lighten
lighten.
lower
lower.
recede
recede.
reduce
cut back.
step-down
step down.
Other relevant words:
abatement, collapse, cut back, cutback, dip, fall, increase, minify, plunge, rebate, shrivel, top-slice.

Usage examples for decrease

  1. But even at this vast distance we are not to halt; imagine that we retreat still further and further; the strain shown by the balance will ever decrease but it will still exist, no matter how far we go. – The Story of the Heavens by Robert Stawell Ball
  2. As the miners decrease there is bound to be trouble with the natives, who are very treacherous. – Wanderings Among South Sea Savages And in Borneo and the Philippines by H. Wilfrid Walker
  3. Such effects, however, tend to decrease as the movement advances, and the education and enlightenment of the masses increase. – The Social Work of the Salvation Army by Edwin Gifford Lamb