cd cd /ˈsiːˈdiː/

adjective

1. Being one hundred more than three hundred  ( 400 , cd , four hundred )
   being one hundred more than three hundred
    The building has four hundred rooms
   The building has four hundred rooms
   

noun

1. The basic unit of luminous intensity adopted under the Système International d'Unités; equal to 1/60 of the luminous intensity per square centimeter of a black body radiating at the temperature of 2,046 degrees Kelvin  ( candela , candle , cd , standard candle )
   the basic unit of luminous intensity adopted under the Système International d'Unités; equal to 1/60 of the luminous intensity per square centimeter of a black body radiating at the temperature of 2,046 degrees Kelvin
   

 CD

1. A digitally encoded recording on an optical disk that is smaller than a phonograph record; played back by a laser  ( CD , compact disc , compact disk )
   a digitally encoded recording on an optical disk that is smaller than a phonograph record; played back by a laser
    I prefer buying compact discs over digital music because I like having a physical copy
   I prefer buying compact discs over digital music because I like having a physical copy
   
   
2. A debt instrument issued by a bank; usually pays interest  ( CD , certificate of deposit )
   a debt instrument issued by a bank; usually pays interest
   

 Cd

1. A soft bluish-white ductile malleable toxic bivalent metallic element; occurs in association with zinc ores  ( atomic number 48 , cadmium , Cd )
   a soft bluish-white ductile malleable toxic bivalent metallic element; occurs in association with zinc ores