Definition of cover letter in US English:

cover letter

(British covering letter)

noun

North American
  • A letter sent with, and explaining the contents of, another document or a parcel of goods.

    ‘remember to include a cover letter when mailing out your prospectus’

Pronunciation

cover letter

/ˈkəvər ˌlɛdər//ˈkəvər ˌledər/