(CNN) -- The concept of pansexuality has been around since the days of Sigmund Freud, but it took a shout-out from Miley Cyrus to bring it back into vogue for the 21st century.

The word has been among Google's top search terms since the pop star declared herself pansexual in an interview with Paper magazine in July.

As she put it, "I am literally open to every single thing that is consenting and doesn't involve an animal and everyone is of age. Everything that's legal, I'm down with. Yo, I'm down with any adult -- anyone over the age of 18 who is down to love me. I don't relate to being boy or girl, and I don't have to have my partner relate to boy or girl."

Scholars and sociologists say Cyrus' description sums up the contemporary interpretation of pansexual, sometimes called omnisexual. It's about as as broad as it gets when it comes to describing who you're sexually attracted to, which is precisely why it appeals to a younger generation that's comfortable with gender and sexual fluidity and doesn't care much for specific labels.

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It refers to sexual attraction.

The term comes from adding the prefix "pan," which means all, to sexuality, suggesting that people who identify as pansexual are not restricted in their sexuality to those of the opposite gender (heterosexuality), to the same gender (homosexuality) or to the binary genders of men and women (bisexuality).

The origin of the term "pansexual" is generally attributed to "pansexualism," a term popularized by Sigmund Freud in the early 1900s to describe the view that most human behavior derived from sexual instincts, said Justin R. Garcia, assistant professor of gender studies and research scientist at the Kinsey Institute at Indiana University.

Most behavioral scientists today don't believe that everything we do has a sexual basis. But Freud's work generated important questions about the direction of sexual desires, Garcia said. And it gave us a word that has evolved with the times.

Today, the term pansexual is used to describe a romantic or sexual attraction focused on traits other than sex or gender. In other words, someone who identifies as pansexual is capable of being attracted to multiple sexes and gender identities, said David Bond, vice president of programs for LGBT crisis intervention group, Trevor Project.

"It might have to do with who you have romantic feelings for or who have a sexual attraction for, and those two can be hand-in-hand or distinct," he said.

It's different from bisexuality.

Bisexuality refers to people attracted to men and women. With more people identifying across the gender spectrum between men and women, pansexuality has emerged as a catch-all that includes everyone else.

"People are adopting it because 'bisexual' partakes of the gender binary. Pansexuality is a way of moving beyond that and a personal recognition that attractions are felt across the gender spectrum," Patricia Johnson and Mark Michaels, co-authors of "Designer Relationships: A Guide to Happy Monogamy, Positive Polyamory and Optimistic Open Relationships," wrote in an email.

"While it's broad in scope and application, it also has the advantage of referring to a full spectrum of attractions rather than being rooted in the idea that attraction is either for the same gender, an 'opposite' gender or both. That inclusivity actually gives it a very specific meaning."

Some prefer it to "bisexuality" because it is encompasses attraction to men, women, transgender people and those who are intersex (born with a sex that doesn't fit the typical definitions of male or female).

However, some sexuality scholars argue that the term "bisexuality" also includes these categories, so the distinction between "pansexual" and "bisexual" is still up for debate, with no consensus on the best terminology.

It's not new, but it's new again.

The term tends to enter the public consciousness through celebrities, and Cyrus is the most recent to claim the title.

The pop star follows other notable people who have recently declared themselves pansexual, including transgender YouTube personality Jazz Jennings and Texas state lawmaker Mary Gonzalez.

Scholars attribute the word's rise to growing acceptance -- especially among millennials and "generation Z" -- of sexual and gender diversity and gender neutral norms.

"It is a broad word, and that is because people want to have the freedom to self-identify any way they want without being labeled by anyone else," said psychotherapist and sex therapist Michael Aaron.

"It has cultural resonance because it is so broad and allows for so much flexibility and choice."

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