WordNet sense 1 (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):

potassium

WordNet sense 2 (the cardinal number that is the product of 10 and 100):

g, grand, m, thou, thousand, yard, chiliad, thou, one thousand

WordNet sense 3 (the basic unit of thermodynamic temperature adopted under the Systeme International d'Unites):

kelvin

WordNet sense 4 (a unit of information equal to one thousand (1024) bytes):

kilobyte, KB

WordNet sense 5 (the 11th letter of the Roman alphabet):

letter k

WordNet sense 6 (street names for ketamine):

green, jet, cat valium, honey oil, special K, super acid, super C

WordNet sense 7 (being or denoting a numerical quantity but not order):

cardinal