1580s, "to estimate the value of; value highly," spelling alteration of Middle English prisen "to reckon the worth of, value, esteem, praise" (late 14c.), from stem of Old French preisier "to praise" (see praise (v.)). Related: Prized; prizing.
1767, "a lowering of value" (originally of currency), noun of action from depreciate. Sense of "a belittling, deliberate underestimation of the merits of a person, action, or thing" is from 1790. Meaning "loss of value of a durable good by age or wear" is from 1900.
1650s, "to esteem or value highly," from Late Latin appretiatus, past participle of appretiare "to set a price to," from ad "to" (see ad-) + pretium "price" (see price (n.)). Meaning "to rise in value" (intransitive) is by 1787; sense of "be fully conscious of" is by 1833. "Appreciate is to set a just value on; it implies the use of wise judgment or delicate perception" [Century Dictionary]. Related: Appreciated; appreciating.
mid-15c., "to undervalue, under-rate," from Latin depretiatus, past participle of depretiare "to lower the price of, undervalue," from de "down" (see de-) + pretium "price" (see price (n.)). From 1640s in transitive sense of "lessen the value of, to lower in value." Intransitive sense of "to fall in value, become of less worth" is from 1790. Related: Depreciated; depreciating.