Polari—a well-developed form of slang spoken by British gay men in the mid-20th century—fell out of favor with the advent of the gay liberation movement, but has enjoyed a revival in recent years.

The origins of Polari are uncertain, but most linguists believe its roots date back at least to the 1800s. Largely derived from Italian, it also includes words drawn from other languages such as Romany, French, and Yiddish. One early form was used by British Merchant Navy seamen who, while traveling around the Mediterranean, often learned the Lingua Franca, a pidgin developed as a means of communication among traders of diverse tongues. Lacking a stable livelihood, many former sailors fell in with itinerant fairground and circus performers—who spoke their own slang known as Parlyaree—and the groups adopted each others’ vocabularies. Polari also includes elements of backslang (words spelled backwards), Cockney rhyming slang, the cant of the criminal underworld, and American military jargon.

Polari remained popular among "sea queens"—gay men who worked as stewards or entertainers aboard passenger ships—and in the 1930s, it came into wider use among queer men in London, both working-class East-Enders and men involved in the West End theater scene. At a time when homosexuality was illegal, Polari offered gays a way of identifying one another and speaking about forbidden topics.

"Gay people sort of adopted it for themselves like a secret language, so they could talk to each other in front of straight people," recalled an anonymous former seaman quoted in a Merseyside Maritime Museum exhibit about gay life at sea. "You could say ‘oh vada the bona eek on the omi,’ and it meant have a look at the nice face on that chap over there, and he wouldn’t know what on earth you were talking about, or you might get a wallop."

While Polari offered a means of protection, it also served to validate identity and build community. "Far too many theorists interpret gay culture as a strategy for coping with or undermining straight culture rather than as having cultural values for its own sake," writes social historian Rictor Norton. "Polari was never designed to escape notice...The origins of most gay argot, in other languages as well as English, can be traced to a core of faggots who couldn’t give a damn about being overheard by respectable people. They used queer language for the purposes of cultural solidarity, not to convey secret messages past the ears of unwitting straights."

Polari was well suited for gossip, insults, ribald humor, and cruising. Traditionally a spoken language with much regional variation, it had no formal written lexicon. Linguist Paul Baker —the foremost academic expert on Polari—estimates that it included as many as 500 words, of which about 20 were widely understood core terms. Polari was largely comprised of adjectives and nouns, with clothing, body parts, and sexual acts particularly well represented. Several words derived from Polari have been adopted into mainstream English, including "camp," "drag," "butch," "cottaging" (cruising for sex in a public toilet), and "zhoosh" (an indefinable term repopularized by Carson Kressley on Queer Eye for the Straight Guy).

Polari came to wide public attention in the mid-1960s, when it was featured on the BBC weekly radio comedy series Round the Horne. The show’s most popular characters, Julian and Sandy—portrayed by Kenneth Williams and Hugh Paddick— were two stereotypically queeny out-of-work actors who dabbled in a variety of improbable business ventures. Many men who lived outside large cities and did not have a circle of gay friends learned Polari from Round the Horne, albeit an abbreviated and sanitized version. According to Baker, "Julian and Sandy were possibly the only accessible gay identities who were able to provide some sort of clue that other people like themselves existed and were part of a subculture."

In the 1970s, Polari went into decline. The 1967 passage of the Sexual Offenses Act, which decriminalized sex between men, reduced the need for a secret language—which was no longer so secret anyway. With the dawn of the gay liberation movement, many queers eschewed the stereotypical bitchiness and campy effeminacy associated with Polari, and found its emphasis on appearance, gossip, and sex politically incorrect—or at least terribly old-fashioned.

Since that time, however, Polari has made somewhat of a comeback. Julian and Sandy reached a new audience with the release of CDs and a stage version of Round the Horne.

Polari has cropped up in popular culture from the television series Dr. Who, to Morrissey’s 1990 Bona Drag album (featuring the song "Picadilly Palare"), to Todd Haynes’ film Velvet Goldmine (1998), to queer hip-hop artist Juha’s 2002 album, Polari.

The British Sisters of Perpetual Indulgence use it for blessings and feature a Polari version of the Bible on their website; the Internet is also home to numerous Polari lexicons.

"[M]ore than a language, Polari is an attitude," says Baker, one that demonstrates how gay men "reconstruct their world and themselves from new perspectives, making sense of experiences that have no existing labels in mainstream culture."