1. A soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal
   - cesium [N. Amer], caesium [Brit, Cdn], atomic number 55

1. The 3rd letter of the Roman alphabet
   - C
    
2. The speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second
   "Nothing can travel faster than c";
   - speed of light, light speed

Type of: alphabetic character, constant, letter, letter of the alphabet, metal, metallic element, speed, velocity

Part of: Latin alphabet, pollucite, Roman alphabet

Encyclopedia: Cs