is a specific kind of: change of magnitude.

is a broader term that covers: cut | mitigation, moderation | lowering | cutback | devaluation | devitalisation, devitalization | extenuation, mitigation, palliation | alleviation, easement, easing, relief | de-escalation | minimisation, minimization | depletion | shortening | shrinking | deduction, subtraction | deflation | deduction, discount, price reduction | rollback | weakening | depreciation | contraction | reverse split, reverse stock split, split down | amortisation, amortization | declassification | shelter, tax shelter | tax credit ... show more.

is the opposite of: increase, step-up.

derivation: decrease, diminish, fall, lessen | reduce, scale down | reduce, shrink | de-escalate, step down, weaken | bring down, cut, cut back, cut down, reduce, trim, trim back, trim down.