1Sometimes with the. The name given to a tree in Boston from which effigies were hung during protests against the Stamp Act in 1765.
The tree became a symbol for the American cause and a popular site for political meetings; it was cut down by British soldiers in 1775.
2(A name given to) any tree designated as a symbol of liberty. Also occasionally: a pole erected as a symbol of liberty; a liberty pole.
Mid 18th century; earliest use found in The Public Advertiser. From liberty + tree.