Definitions:

1. Abbreviation for '1000', especially 1000 pounds, dollars, etc. ABBREVIATION
   • His car cost him $20K.
2. Abbreviation for 'Kilometer'. ABBREVIATION
   • She's training to run her first 10K this summer.
3. Abbreviation for 'Kindergarten'. ABBREVIATION
4. Chemical symbol for the element 'potassium'. NOUN
5. The eleventh letter of the English alphabet. NOUN

Synonyms:

• thousand