Secret society

A secret society is a club or an organization whose activities, events, inner functioning, or membership are concealed. The society may or may not attempt to conceal its existence. The term usually excludes covert groups, such as intelligence agencies or guerrilla warfare insurgencies, that hide their activities and memberships but maintain a public presence.[2]

"Secret Society Buildings at Yale College", by Alice Donlevy[1] ca. 1880. Pictured are: Psi Upsilon (Beta Chapter), 120 High Street. Left center: Skull and Bones (Russell Trust Association), 64 High Street. Right center: Delta Kappa Epsilon (Phi Chapter), east side of York Street, south of Elm Street. Bottom: Scroll and Key (Kingsley Trust SSS Nonse Association), 490 College Street.