The Collaborative International Dictionary of English v.0.48:

Dais \Da"is\ (d[=a]"[i^]s), n. [OE. deis, des, table, dais, OF.
   deis table, F. dais a canopy, L. discus a quoit, a dish (from
   the shape), LL., table, fr. Gr. ? a quoit, a dish. See
   Dish.]
   1. The high or principal table, at the end of a hall, at
      which the chief guests were seated; also, the chief seat
      at the high table. [Obs.]
      [1913 Webster]

   2. A platform slightly raised above the floor of a hall or
      large room, giving distinction to the table and seats
      placed upon it for the chief guests.
      [1913 Webster]

   3. A canopy over the seat of a person of dignity. [Obs.]
      --Shiply.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dais
    n 1: a platform raised above the surrounding level to give
         prominence to the person on it [syn: dais, podium,
         pulpit, rostrum, ambo, stump, soapbox]