liberty cap

noun

1. a soft, conical cap given to a freed slave in ancient Rome at manumission of his servitude, used as a symbol of liberty, especially since the 18th century.

noun

1. a cap of soft felt worn as a symbol of liberty, esp during the French Revolution, from the practice in ancient Rome of giving a freed slave such a cap
2. a poisonous hallucinogenic basidiomycetous fungus, Psilocybe semilanceata, yellowish-brown with a distinctive pointed cap, found in groups in grassland