Uncle Tom see under uncle

uncle /ungˈkl/

1. The brother of one's father or mother, or an aunt's husband, or a great-uncle (used with cap as a title, either before a man's first name or independently)
2. Used as a form of address to an elderly, esp black, man (chiefly US)
3. A pawnbroker (slang)
4. (with cap) a title sometimes used by children for male friends of their parents

To address as uncle

unˈcleship noun

The state of being an uncle

uncle Dick or Uncle Dick adjective (Cockney rhyming sl)

Sick

Uncle Sam noun

The United States or its people

Uncle Tom noun (US derogatory)

A black American whose co-operative attitude to white people is thought to show disloyalty to black people (based on the hero of Harriet Beecher-Stowe's Uncle Tom's Cabin (1851–2))

cry or say uncle (US)

To surrender or admit defeat