Original: Queen's Counsel (postnominal QC), known as King's Counsel (KC) during the reign of a male sovereign, are lawyers appointed by letters patent to be one of "Her [or His] Majesty's Counsel learned in the law".
Simplified: Queen's Counsel (postnominal QC), during the reign of a male sovereign known as King's Counsel (KC), are senior lawyers in various Commonwealth countries. They are appointed by letters patent to be one of "Her Majesty's Counsel learned in the law".