tr.v. en·er·vat·ed, en·er·vat·ing, en·er·vates
To weaken or destroy the strength or vitality of: "the luxury which enervates and destroys nations" (Henry David Thoreau). See Synonyms at deplete.
Medicine To remove a nerve or part of a nerve.
Deprived of strength; debilitated.
[Latin ēnervāre, ēnervāt- : ē-, ex-, ex- + nervus, sinew; see (s)neəu- in Indo-European roots.]
en'er·va'tion n., en'er·va'tive adj., en'er·va'tor n.
Usage Note: Sometimes people mistakenly use enervate to mean "to invigorate" or "to excite" by assuming that this word is a close cousin of the verb energize. In fact enervate does not come from the same source as energize (Greek energos, "active"). It comes from Latin nervus, "sinew." Thus enervate means "to cause to become 'out of muscle'," that is, "to weaken or deplete of strength."
This is one of my favorite words because as the usage note states the meaning is so opposite of what you'd expect. It even beats out pulchritude on that score!!!