The Collaborative International Dictionary of English v.0.48:

Grate \Grate\, v. i.
   1. To make a harsh sound by friction.
      [1913 Webster]

            I had rather hear a brazen canstick turned,
            Or a dry wheel grate on the exletree. --Shak.
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   2. To produce the effect of rubbing with a hard rough
      material; to cause wearing, tearing, or bruising. Hence;
      To produce exasperation, soreness, or grief; to offend by
      oppression or importunity.
      [1913 Webster]

            This grated harder upon the hearts of men. --South.
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The Collaborative International Dictionary of English v.0.48:

Grate \Grate\, n. [LL. grata, fr. L. crates hurdle; or It.
   grata, of the same origin. Sae Crate, Hurdle.]
   1. A structure or frame containing parallel or crosed bars,
      with interstices; a kind of latticework, such as is used
      ia the windows of prisons and cloisters. "A secret grate
      of iron bars." --Shak.
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   2. A frame or bed, or kind of basket, of iron bars, for
      holding fuel while burning.
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   Grate surface (Steam, Boiler) the area of the surface of
      the grate upon which the fuel lies in the furnace.
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The Collaborative International Dictionary of English v.0.48:

Grate \Grate\, v. t. [imp. & p. p. Grated; p. pr. & vb. n.
   Grating.]
   To furnish with grates; to protect with a grating or
   crossbars; as, to grate a window.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grate \Grate\, v. t. [OF grater to scrape, scratch, F. gratter,
   LL. gratare, cratare; of German origin; cf. OHG. chrazz[=o]n
   G. kratzen, D. krassen, Sw. Kratta, and perh. E. scratch.]
   1. To rub roughly or harshly, as one body against another,
      causing a harsh sound; as, to grate the teeth; to produce
      (a harsh sound) by rubbing.
      [1913 Webster]

            On their hinges grate
            Harsh thunder.                        --Milton.
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   2. To reduce to small particles by rubbing with anything
      rough or indented; as, to grate a nutmeg.
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   3. To fret; to irritate; to offend.
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            News, my good lord Rome . . . grates me. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Grate \Grate\, a. [L. gratus agreeable, grateful: cf. It. & Sp.
   grato. See Grace, and cf. Agree.]
   Serving to gratify; agreeable. [Obs.] --Sir T. Herbert.
   [1913 Webster]

WordNet (r) 3.0 (2006):

grate
    n 1: a frame of iron bars to hold a fire [syn: grate,
         grating]
    2: a harsh rasping sound made by scraping something
    3: a barrier that has parallel or crossed bars blocking a
       passage but admitting air [syn: grate, grating]
    v 1: furnish with a grate; "a grated fireplace"
    2: gnaw into; make resentful or angry; "The injustice rankled
       her"; "his resentment festered" [syn: eat into, fret,
       rankle, grate]
    3: reduce to small shreds or pulverize by rubbing against a
       rough or sharp perforated surface; "grate carrots and
       onions"; "grate nutmeg"
    4: make a grating or grinding sound by rubbing together; "grate
       one's teeth in anger" [syn: grate, grind]
    5: scratch repeatedly; "The cat scraped at the armchair" [syn:
       scrape, grate]