The phrase "slave masters" refers to people who were in control of slaves during a time in history when slavery was permitted. They would own and have power over the lives and labor of these enslaved individuals. Full definition
A son and grandson of slaves, Nat, at a young age, was provided the unique opportunity to learn how to read by the sister of his white slave master. (lights-camera-jackson.com)
The lack of a slave cap meant the fat slave master would guarantee me for six months. (bookbrowse.com)
While mutinous slaves may not be able to save themselves, by rebelling they can reduce the number of slave masters who prey on nearby relatives. (discovermagazine.com)