Look at this ruler.

You might describe it as something with no curves and swerves, or long and straight, but then again, you might also use the same word, "straight," to describe someone else's sexuality when they're attracted to someone of the opposite sex.

Wait, what?

This doesn't quite add up.

So, today, let's get to the bottom of the long and winding road of how "straight" came to be synonymous with sexuality.

[upbeat music] Okay, so before we can get into how a word like straight came to mean heterosexual, we have to quickly talk about how and why people started categorizing sexuality in the first place.

The idea that someone could be hetero, homo, or bisexual, or any configuration of LGBTQIA identities really isn't that old at all.

While most historians agree that there's evidence of same-sex romantic relationships in nearly every documented culture, the realities of the people who engaged in them weren't really categorized as "gay."

The same goes for heterosexuality, which only showed up about a century ago under a definition that might be confusing to people today.

That definition for heterosexuality came to us in the late 1860s when Austrian-Hungarian journalist Karl Maria Kertbeny coined it in a letter to German lawyer and author Carl Heinrich Ulrichs, whom Kertbeny met on his travels and considered a contemporary.

Today, Ulrichs is known as an early pioneer in the gay rights movement.

In the letter, the term appeared with three other terms as well-- homosexuality, monosexual, and heterogenic.

Those last two meant masturbation and bestiality, respectively.

If that makes heterosexual sound more like a diagnosis than an identity, well, that's because it kind of was.

In the 1880 book, "The Discovery of the Soul," the word heterosexual in German debuted to a wide audience.

A few years later, in 1892, the word appeared in English in "Psychopathia Sexualis," and in 1901, Dorland's medical dictionary defined heterosexuality as: an "abnormal or perverted appetite towards the opposite sex."

When the term appeared in Miriam Webster's dictionary for the first time in 1923, it touted the definition, "a morbid sexual passion for one of the opposite sex."

Wait, hold on.

Does that mean heterosexuality used to be seen as deviant behavior?

Were straight people being oppressed for being straight?

Well, no.

It's just that what we now know as heterosexuality was so accepted as the norm back then that nobody felt the need to go out of their way to define it, and when they did, it was to pathologize all manner of sexual behavior that would've been seen as taboo.

In 1934, heterosexuality adopted a meaning that might look more familiar to us today, although it might elicit a few justified "Yikes."

Its updated definition in Miriam Webster called it a "manifestation of sexual passion for one of the opposite sex; normal sexuality."

Keep that last part, "normal sexuality," in mind because it's gonna come up again with "straight," which we'll finally get to now.

Sorry, I guess the path to the word straight is pretty loopy.

The first documented appearance of the word straight as a descriptor for heterosexuality is in American psychiatrist, G. W. Henry's, 1941 book titled "Sex Variants," which sought to follow the experiences of 80 lesbians and gay men in New York City in the 1930s.

In it, there's the definition, "To go straight "is to cease homosexual practices and to indulge, usually to re-indulge, in heterosexuality."

Because heterosexuality is oh-so-indulgent.

In case you missed the subtext here, the book is saying that the word "straight" actually started out as gay slang, as an in-community way to describe someone who was, if I may use the term that wasn't popular in the vocabulary back then, re-closeting themselves.

Someone was "going straight" if they dropped out of the scene or entered a heterosexual relationship.

As is often the case with slang, it was laced with irony and sarcasm.

The gay community was likely playing off the common colloquial phrase "straight and narrow," which is defined in the Cambridge dictionary as, "Behaving in a way that is honest and moral."

This old saying has its roots in the Bible, specifically the Gospel of Matthew 7:13-14, which in the King James version says, "Enter you in at the strait gate: for wide is the gate, "and broad is the way that leads to destruction... "Because strait is the gate, and narrow is the way which leadeth onto life."

A strait, or s-t-r-a-i-t, like the Bering Strait, is a narrow passageway.

Thus to live righteously is to walk the "strait and narrow," which later got changed to the homophone "straight and narrow."

This all relates back to what some scholars would call lavender linguistics, which looks into how LGBTQIA people use language as a vehicle to communicate nuances and identity and their lived experiences.

It's based on the idea that certain communities, especially marginalized ones, will utilize the dominant language in unique ways to make a home for themselves in it.

Looking at it that way, it's no wonder so much slang comes from groups of people who are often othered in mainstream culture.

For more examples of lavender linguistics, we can look at other slang terms that have come up out of gay communities.

Tea, a word that means the truth, be it sipped or spilled or what have you, originated in Black drag culture.

Merriam Webster gives an example of this use of "tea" from 1994 in which the Lady Chablis, a Black drag performer and female impersonator, defines it as, "My thing, my business, what's going on in my life."

But the term "straight" wasn't limited to gay community slang.

Its strong relationship to morality meant it was often dispatched as a catchall for someone who was defined by their abstinence from debauchery, and by the 1970s, the term was concretely established as a synonym for virtuous.

Just take a look at some of 20th century pop culture's weirdest examples, like the Modern Lover song from the 1970s titled, "I'm Straight," in which singer Jonathan Richmond compares himself to a woman's stoner boyfriends.

When he calls himself "straight" in the song, he's not calling himself heterosexual.

He's saying that he's not a drug user.

That's not just a one-off example either.

Look at straight-edge culture that formed in the early '80s in response to the punk culture of the 1970s, the latter of which was big on drug use.

The term was coined by the band Minor Threat in their song "Straight Edge," the lyrics of which bragged about having better things to do than drugs.

People who use "straight edge" to define themselves used to and still do define it as abstinence from drugs, alcohol, and sometimes promiscuous sex.

Though it has been applied in many ways, one thing is for sure-- straight as a slang word has a strong relationship to ideas of morality.

The use of straight to mean "not gay" has a lot to say about how people viewed homosexuality back then, as an act of deviancy alongside other socially taboo activities like gambling and drug use.

It's a view that sadly persists to this day, but back when the words we used to describe sexual orientation were still crystallizing, the word straight was broad enough to cast a person as distinct from all kinds of marginalized groups and misfits.

It's these moral implications that have caused some LGBTQ advocates to push for abolishing the term altogether.

You know, one thing that might surprise a lot of people when they dig into the history of words like gay or straight or heterosexuality is that, relatively speaking, they're really not that old.

What this could tell us is that the book isn't closed on any of these terms.

That's true for language in general.

It's a living, evolving thing, as we've seen in this journey through medical terms, lavender linguistics, and community slang.

I mean, just look at the roaring debate over whether it's okay to describe people as cisgender, a word that means "not transgender" or a person whose sense of personal identity and gender corresponds with their birth sex.

We have words like non-binary for people who don't identify as a man or a woman, and Latinx for people of Latin American descent who want to eschew the gendered nature of Spanish.

Some critics have accused LGBTQ activists of destroying language and making up words, but isn't that kind of how words work?

They have to come from somewhere, and the context they're created in matters a lot.

Plus, all of them were made up by someone at some point.

It's why the dictionary gets updated every year.

So, it could very well be the case that straight won't be around forever as a way to describe heterosexuality.

Its past as a way to contrast heterosexuality against homosexuality in a moral context speaks to a painful history of discrimination and bigotry, but it also speaks to a colorful tradition of marginalized groups creating their own language and their own slang to creatively communicate with each other under difficult conditions.