(n.) The act of undervaluing; a rate or value not equal to the real worth.

abatement ablation abridgment agio alleviation allowance attenuation attrition backbiting backstabbing bank discount belittlement belittling break breakage calumny cash discount chain discount charge-off cheapening comedown concession consumption contempt contraction curtailment cut cutting dampening damping debasement decadence decadency declension declination decline decrease decrement decrescence decrial deduction defamation deflation deformation degeneracy degenerateness degeneration degradation demotion denigration depletion depravation depravedness deprecation depression derogation descent deterioration detraction devaluation devolution diminishment diminution dip disapproval discommendation discount discrediting disgrace disparagement dispraise dissipation disvaluation dive downtrend downturn downward mobility downward trend drain drawback drop dying dying off ebb effeteness erosion evaporation exhaustion expenditure extenuation extraction fade-out fading failing failure failure of nerve faint praise fall falling-off impairment impoverishment indignity involution kickback knocking languishment lapse leakage lessening letup loss of tone lowering lukewarm support markdown miniaturization minimization minimizing misestimation misprision misprizal misprizing mitigation nose dive penalty penalty clause percentage plummet plummeting plunge premium price cut price fall price reduction price-cut putting down rebate rebatement reduction refund regression relaxation remission retraction retrenchment retrocession retrogradation retrogression ridicule rollback sag sagging salvage scaling down scandal setoff shortening shrinkage simplicity slander slash slighting slippage slump sour grapes subtraction tale tare time discount trade discount tret truncation underestimate underestimation underrating underreckoning underselling undervaluation using using up wane wastage waste weakening wearing wearing away write-off