liberty cap

Short definition from Wiktionary

Noun

1. 1
   A brimless felt cap, such as the Phrygian cap or pileus, emblematic of a slave's manumission in the ancient world.
2. 2
   A magic mushroom, a mushroom of the genus Psilocybe, especially Psilocybe semilanceata.

Proper noun

1. 1
   A celebrated granite dome in Yosemite National Park, California, United States.
2. 2
   An unusual hot spring in Yellowstone National Park, United States.
3. 3
   A prominent peak on Mount Rainier, Washington, United States.