The Collaborative International Dictionary of English v.0.48:

Landau \Lan"dau\, n. [From the town Ladau in Germany; cf. F.
   landau. See Land, Island.]
   A four-wheeled covered vehicle, the top of which is divided
   into two sections which can be let down, or thrown back, in
   such a manner as to make an open carriage. [Written also
   landaw.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

Landau
    n 1: Soviet physicist who worked on low temperature physics
         (1908-1968) [syn: Landau, Lev Davidovich Landau]
    2: a four-wheel covered carriage with a roof divided into two
       parts (front and back) that can be let down separately