de·pre·ci·ate 
(dĭ-prēshē-āt′)
(dĭ-prēshē-āt′)v. de·pre·ci·at·ed, de·pre·ci·at·ing, de·pre·ci·ates
v.tr.
1. To lessen the price or value of: An increase in the supply of money depreciated the currency.
2. To write off an expenditure for (a tangible asset) by prorating over a certain period, usually the estimated useful life of the asset.
3. To think or speak of as being of little worth; belittle. See Synonyms at disparage. See Usage Note at deprecate.
v.intr.
To diminish in price or value: "When issued in excess, as during the Revolution, paper depreciated in value" (Daniel Feller).
[Medieval Latin dēpreciāre, dēpreciāt-, alteration of Latin dēpretiāre : dē-, de- + pretium, price; see per-5 in the Appendix of Indo-European roots.]
de·precia·ble (-shə-bəl) adj.
de·preci·a′tor n.