depreciation (n.)

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.

"a lowering of the value of oneself," 1827; see self- + depreciation. Related: Self-depreciating.