/uyn"stuyn/ ; Ger. /uyn"shtuyn'/ , n.
1. Albert /al"beuhrt/ ; Ger. /ahl"berddt/ , 1879-1955, German physicist, U.S. citizen from 1940: formulator of the theory of relativity; Nobel prize 1921.
2. Alfred /al"frid/ ; Ger. /ahl"frddet/ , 1880-1952, German musicologist in U.S.
3. ( l.c. ) Physics, Chem. a unit of radiant energy, equal to the energy of radiation that is capable of photochemically changing one mol of a photosensitive substance.