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Webster 1828 Edition

ppr.

Lessening the price or worth; undervaluing.

Falling in value.

depreciating

depreciating ‎(comparative more depreciating, superlative most depreciating)

That is declining in value.
That degrades the value of something; deprecating.
- 1887, Sir Arthur Conan Doyle, A Study in Scarlet, VII:
  Gregson and Lestrade seemed to be far from satisfied by this assurance, or by the depreciating allusion to the detective police.