Uncle Tom /ˌʌŋk ə l ˈtɒm $ -ˈtɑːm/ BrE AmE noun [countable]
[ Date: 1800-1900 ; Origin: Uncle Tom black slave in the book Uncle Tom's Cabin (1852) by Harriet Beecher Stowe ]
American English a black person who is too respectful to white people – used to show disapproval