Language matters. Words shape how we understand each other, how we interact with our communities, and how we either uphold or dismantle systems of oppression. In recent years, terms like “biological sex”, “biological male”, “biological female”, “biologically male”, “biologically female”, and “biological reality” have become increasingly weaponised. These phrases, often presented as scientific or neutral, have in fact become dog whistles for transphobia. They are used not to clarify, but to dehumanise. Not to inform, but to exclude.
Let us be clear: these terms, as they are currently deployed in media, politics, and public discourse, function as transphobic slurs.
Language, Respect, and the Power of Self-Definition
A fundamental principle of equality and respectful coexistence is to refer to communities by the language they use to describe themselves. We do not use anti-Semitic labels to refer to Jewish people. We do not describe gay people with terms popularised by homophobes, even if such language once held mainstream currency. The same principle must apply to trans people.
It is not neutral to call a trans woman a “biological man.” It is not scientific to describe a trans man as a “biological female.” It is not scientific to describe sex or gender as a “biological binary.” It is an act of deliberate misgendering. It erases the reality of trans people’s lives and identities. It frames them, falsely, as deceptive or unnatural. And it promotes the idea — long debunked, yet stubbornly persistent — that trans people are merely pretending to be something they are not.
The Pseudoscience of “Biological Reality”
The recent open letter from a coalition of biologists, doctors, and other experts to the Minister for Women and Equalities rightly pointed out that “biological sex” is not a well-defined or fixed term. As they wrote:
“The terms ‘biological woman’ and ‘biological man’… are often not used as scientific terms but political ones. To our knowledge, neither the [Supreme] court nor the EHRC has attempted to define ‘biological sex.’”
That’s because defining sex as a singular, immutable binary is scientifically indefensible. As scientists across multiple disciplines have confirmed, what we colloquially call “biological sex” is in fact a complex, overlapping set of traits: chromosomes, hormones, internal and external anatomy, secondary sex characteristics, and more. These vary widely across individuals and do not always align.
For instance:
- Some people with XY chromosomes are born with a ‘typically female external anatomy’.
- Intersex people exist, despite constant political attempts to erase them from public consciousness.
- Hormones, gene expression, and body composition are all deeply responsive to medical treatment and change over time.
Sex, like gender, exists across spectra, not fixed points.
This matters deeply in medical contexts. To take one example from the letter:
“A trans woman taking oestrogen for a short period of time would experience a reduction in her haemoglobin level. To use ‘birth sex’ reference ranges for a blood test in this case would be inappropriate… with the potential for misdiagnosis, over-investigation and harm.”
In other words, insisting on “biological sex” as a basis for care or classification is not just inaccurate, it can be dangerous.
The Political Weaponisation of “Biological”
The terms in question — “biological woman”, “biological man”, “biologically male”, “biologically female”, “biological sex”, and “biological reality” — are not value-neutral descriptors. They are deliberately chosen by those seeking to deny the legitimacy of trans people’s identities, lives, and rights.
These terms are:
- Used primarily by anti-trans activists to reduce people to the body they were assigned at birth.
- Rejected by trans people ourselves — in favour of medically accurate, contextually appropriate terms like “trans man,” “trans woman,” “cisgender,” and “assigned sex at birth.”
- Not standard clinical terminology, and are absent from the diagnostic frameworks of the World Health Organization, NHS guidance, or contemporary endocrinology and gender-affirming care protocols.
- Designed to deny personhood — asserting that trans women are “really” men, or that trans men are “really” women, no matter how long they’ve lived in their gender, or what medical steps they’ve taken.
And yet, politicians, columnists, and even some institutions continue to parrot these terms under the pretence of “speaking plainly” or “telling the truth.” What they are doing, in reality, is advancing a political ideology rooted in “biological essentialism” and the denial of human complexity.
This Is About Power, Not Precision
The use of these terms in public discourse has never been about accuracy. It has always been about asserting power, the power to name others, to define the terms of debate, and to strip people of their dignity with plausible deniability.
Calling a trans woman a “biological male” is not a neutral fact. It is a slur. It is an attempt to strip her of womanhood, of social legitimacy, of safety. It is no different than calling a gay man by a homophobic epithet under the guise of “just being honest.”
If you wouldn’t use the n-word to refer to a Black person — even if you claimed it once had clinical or descriptive roots — then you understand the principle. Some words are not yours to use. Not because of censorship, but because of respect, safety, and human decency.
A Call to Change the Terms
We are calling on journalists, politicians, educators, health professionals, and public bodies to immediately cease the use of the following terms in reference to trans people:
- “biological sex”
- “biological male”
- “biological female”
- “biologically male”
- “biologically female”
- “biological man”
- “biological woman”
- “biological reality”
- “biological binary”
- “biological essentialism”
- “natal male/female”
- “natal man/woman”
- “genetic male/female”
- “chromosomal sex”
- “trans woman who was born a man”
- “trans man who was born a woman”
- “trans woman who was born male”
- “trans man who was born female”
- “trans-identifying male”
- “trans-identifying female”
- “male/female bodied”
These terms are not only inaccurate, they are inflammatory. They are tools of oppression disguised as statements of fact.
Instead, adopt the language the community uses: trans woman, trans man, non-binary person, cisgender, assigned female/male at birth (AFAB/AMAB), and intersex. These terms are recognised in medical literature, used in clinical care, and — most importantly — reflect how people identify and move through the world.
We must abandon the pretence that this debate is merely semantic or scientific. It is not. It is about the fundamental right of people to exist as themselves without being linguistically misgendered or legally erased.