The Collaborative International Dictionary of English v.0.48:

Sprinkler \Sprin"kler\ (-kl[~e]r), n.
   1. One who sprinkles.
      [1913 Webster]

   2. An instrument or vessel used in sprinkling; specifically,
      a watering pot.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sprinkler
    n 1: mechanical device that attaches to a garden hose for
         watering lawn or garden

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "sprinkler":
   Agnus Dei, Foamite, Holy Grail, Host, Pieta, Sanctus bell,
   Sangraal, acid, aerosol, ark, asperger, asperges, aspergil,
   aspergillum, atomizer, automatic sprinkler, bambino, beadroll,
   beads, candle, carbon tet, carbon tetrachloride,
   carbon-dioxide foam, censer, chaplet, ciborium, clyster,
   concentrate sprayer, cross, crucifix, cruet, deck gun, deluge set,
   douche, enema, eucharistial, extinguisher, fire apparatus,
   fire engine, fire hose, fire hydrant, fireplug, foam,
   foam extinguisher, fountain syringe, holy cross, holy water,
   holy-water sprinkler, hook-and-ladder, icon, incensory,
   ladder pipe, matzo, menorah, mezuzah, mikvah,
   mist concentrate sprayer, monstrance, needle bath, nozzle,
   osculatory, ostensorium, paschal candle, pax, phylacteries,
   prayer shawl, prayer wheel, pumper, pyx, relics, rood, rosary,
   sacramental, sacred relics, sacring bell, shofar, shower,
   shower bath, shower head, snorkel, soda, sparge, sparger, spray,
   spray can, sprayer, sprinkler head, sprinkler system,
   sprinkling system, sukkah, super-pumper, syringe, tabernacle,
   tallith, thurible, urceole, veronica, vigil light, votive candle,
   water, water cannon, watercart, watering can, watering pot,
   wet blanket