The Collaborative International Dictionary of English v.0.48:

Stopple \Stop"ple\, v. t. [imp. & p. p. Stoppled; p. pr. & vb.
   n. Stoppling.]
   To close the mouth of anything with a stopple, or as with a
   stopple. --Cowper.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stopple \Stop"ple\, n. [Cf. G. st["o]pfel, st["o]psel. See
   Stop, n. & v. t.]
   That which stops or closes the mouth of a vessel; a stopper;
   as, a glass stopple; a cork stopple.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stopple
    n 1: blockage consisting of an object designed to fill a hole
         tightly [syn: plug, stopper, stopple]
    v 1: close or secure with or as if with a stopper; "She
         stoppered the wine bottle"; "The mothers stoppered their
         babies' mouths with pacifiers" [syn: stopper, stopple]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "stopple":
   bar, bind, block, block up, blockade, bung, caulk, check valve,
   chink, choke, choke off, choke up, clog, clog up, cock, congest,
   constipate, cork, cover, dam, dam up, faucet, fill, fill up, foul,
   jam, lid, obstipate, obstruct, pack, peg, pin, plug, plug up,
   sea cock, spigot, spike, spile, spill, stanch, stay, stench, stop,
   stop up, stopgap, stopper, stuff, stuff up, tap, valve