The Collaborative International Dictionary of English v.0.48:

Patter \Pat"ter\, v. t.
   1. To spatter; to sprinkle. [R.] "And patter the water about
      the boat." --J. R. Drake.
      [1913 Webster]

   2. [See Patter, v. i., 2.] To mutter; as prayers.
      [1913 Webster]

            [The hooded clouds] patter their doleful prayers.
                                                  --Longfellow.
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   To patter flash, to talk in thieves' cant. [Slang]
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The Collaborative International Dictionary of English v.0.48:

Patter \Pat"ter\, n.
   1. A quick succession of slight sounds; as, the patter of
      rain; the patter of little feet.
      [1913 Webster]

   2. Glib and rapid speech; a voluble harangue.
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   3. The cant of a class; patois; as, thieves's patter;
      gypsies' patter.
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   4. The language or oratory of a street peddler, conjurer, or
      the like, hence, glib talk; a voluble harangue; mere talk;
      chatter; also, specif., rapid speech, esp. as sometimes
      introduced in songs. [Cant or Colloq.]
      [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Patter \Pat"ter\, v. i. [imp. & p. p. Pattered; p. pr. & vb.
   n. Pattering.] [Freq. of pat to strike gently.]
   1. To strike with a quick succession of slight, sharp sounds;
      as, pattering rain or hail; pattering feet.
      [1913 Webster]

            The stealing shower is scarce to patter heard.
                                                  --Thomson.
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   2. To mutter; to mumble; as, to patter with the lips.
      --Tyndale. [In this sense, and in the following, perh.
      from paternoster.]
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   3. To talk glibly; to chatter; to harangue. [Colloq.]
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            I've gone out and pattered to get money. --Mayhew.
      [1913 Webster]

WordNet (r) 3.0 (2006):

patter
    n 1: plausible glib talk (especially useful to a salesperson)
         [syn: spiel, patter, line of gab]
    2: a quick succession of light rapid sounds; "the patter of
       mice"; "the patter of tiny feet"
    v 1: rain gently; "It has only sprinkled, but the roads are
         slick" [syn: sprinkle, spit, spatter, patter,
         pitter-patter]
    2: make light, rapid and repeated sounds; "gently pattering
       rain" [syn: patter, pitter-patter]

Moby Thesaurus II by Grady Ward, 1.0:

256 Moby Thesaurus words for "patter":
   Scotch mist, act, act as foil, acting, appear, argot, babble,
   babbling, ballyhoo, bang, barnstorm, barrage, baste, batter, beat,
   beat a ruffle, beat a tattoo, beating, blab, blabber, blather,
   blether, blood rain, buffet, buffoonery, bump, business, cackle,
   cant, chaffer, characterization, chat, chatter, chink, clack,
   clatter, click, clink, clop, clump, clunk, colloquialize, come out,
   converse, crump, declaim, dither, drizzle, drub, drum, drum music,
   drumbeat, drumfire, drumming, dull thud, emote, emotionalize,
   evening mist, fall, flail, flap, flick, flump, flurry, flutter,
   gab, gabble, gabbling, gag, gas, get top billing, gibber,
   gibberish, gibble-gabble, go on, go pitapat, gobbledygook, gossip,
   gout of rain, gush, ham, hammer, hammy acting, haver, hoke, hokum,
   hot air, impersonation, jabber, jabbering, jargon, jargonize, jaw,
   knock, lambaste, larrup, line, lingo, maul, mime, mimesis,
   mimicking, mimicry, miming, mist, misty rain, mizzle, moisture,
   mouth, mumbo jumbo, mummery, natter, overacting, pad, palaver,
   palpitate, palpitation, pantomime, pantomiming, paradiddle, paste,
   pat, patois, pelt, perform, performance, performing, personation,
   phraseology, pitapat, pitch, pitter-patter, play, play the lead,
   playact, playacting, playing, plump, plunk, pommel, pop, portrayal,
   pound, pounding, pour, pour forth, pour with rain, prate, prattle,
   precipitate, precipitation, projection, pulsate, pulsation,
   pulverize, pummel, rain, rain tadpoles, raindrop, rainfall,
   rainwater, ramble on, rap, rat-a-tat, rat-tat, rat-tat-tat,
   rataplan, rattattoo, rattle, rattle on, reel off, register,
   representation, roll, rub-a-dub, ruff, ruffle, run on, sales pitch,
   sales talk, scatology, scurry, scuttle, sheet of rain, shower,
   shower down, sketch, skip, slang, slapstick, sledgehammer,
   small talk, sound a tattoo, spank, spatter, spattering, speak,
   spiel, spit, splatter, splutter, spout, spout off, sprinkle,
   sputter, staccato, stage business, stage directions,
   stage presence, star, steal the show, stooge, stream, stunt,
   taboo language, taking a role, talk, talk away, talk nonsense,
   talk on, tap, tat-tat, tattoo, thrash, thresh, throb, throbbing,
   thrum, thud, thump, thumping, tick, tinkle, tiptoe, tittle-tattle,
   tom-tom, tread the boards, trip, troupe, tunk, twaddle, twattle,
   unfrozen hydrometeor, upstage, use language, vernacular,
   vocabulary, vulgar language, waffle, wag the tongue, wallop, weep,
   wet, whip, yak, yakkety-yak