The Collaborative International Dictionary of English v.0.48:

Scarlet \Scar"let\, a.
   Of the color called scarlet; as, a scarlet cloth or thread.
   [1913 Webster]

   Scarlet admiral (Zool.), the red admiral. See under Red.
      -- Scarlet bean (Bot.), a kind of bean (Phaseolus
      multiflorus) having scarlet flowers; scarlet runner.

   Scarlet fever (Med.), a contagious febrile disease
      characterized by inflammation of the fauces and a scarlet
      rash, appearing usually on the second day, and ending in
      desquamation about the sixth or seventh day.

   Scarlet fish (Zool.), the telescope fish; -- so called from
      its red color. See under Telescope.

   Scarlet ibis (Zool.) See under Ibis.

   Scarlet maple (Bot.), the red maple. See Maple.

   Scarlet mite (Zool.), any one of numerous species of bright
      red carnivorous mites found among grass and moss,
      especially Thombidium holosericeum and allied species.
      The young are parasitic upon spiders and insects.

   Scarlet oak (Bot.), a species of oak (Quercus coccinea)
      of the United States; -- so called from the scarlet color
      of its leaves in autumn.

   Scarlet runner (Bot.), the scarlet bean.

   Scarlet tanager. (Zool.) See under Tanager.
      [1913 Webster]

WordNet (r) 3.0 (2006):

scarlet runner
    n 1: tropical American bean with red flowers and mottled black
         beans similar to Phaseolus vulgaris but perennial; a
         preferred food bean in Great Britain [syn: scarlet
         runner, scarlet runner bean, Dutch case-knife bean,
         runner bean, Phaseolus coccineus, Phaseolus
         multiflorus]
    2: hairy trailing or prostrate western Australian vine with
       bright scarlet-pink flowers [syn: scarlet runner, running
       postman, Kennedia prostrata]
    3: long bean pods usually sliced into half-inch lengths; a
       favorite in Britain [syn: scarlet runner, scarlet runner
       bean, runner bean, English runner bean]