The noun has 5 meanings:

Meaning #1: the basic unit of thermodynamic temperature adopted under the System International d'Unites
  Synonym: kelvin

Meaning #2: a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite
  Synonyms: potassium, atomic number 19

Meaning #3: the cardinal number that is the product of 10 and 100
  Synonyms: thousand, one thousand, 1000, M, chiliad, G, grand, thou, yard

Meaning #4: a unit of information equal to 1024 bytes
  Synonyms: kilobyte, KB

Meaning #5: the 11th letter of the Roman alphabet