References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Sexual health comes with its own vocabulary. From medical terms to slang, knowing what things mean helps you understand test results, treatment options and health information. Here’s a plain-English guide to the most commonly used sexual health terms.
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Common Terms
| Term | Meaning |
|---|---|
| Abstinence | Not having sex |
| Antibody | Protein your body makes to fight infection |
| Antigen | Part of a virus or bacteria that triggers immune response |
| ART | Antiretroviral therapy — HIV treatment |
| Asymptomatic | Having no symptoms despite infection |
| CD4 | Immune cells HIV targets |
| Cervical screening | Test for cell changes on the cervix |
| Condom | Barrier protection against STIs and pregnancy |
| Dysuria | Pain or burning when urinating |
| NAAT | Nucleic acid amplification test — the standard STI test |
| PEP | Post-exposure prophylaxis — emergency HIV prevention |
| PrEP | Pre-exposure prophylaxis — ongoing HIV prevention |
| Seroconversion | When the body first makes antibodies to HIV |
| STI | Sexually transmitted infection |
| U=U | Undetectable = Untransmittable (HIV) |
| Viral load | Amount of virus in the blood |
| Window period | Time between infection and reliable test detection |
Why Terminology Matters
Understanding these terms helps you have informed conversations with clinicians, understand test results and make better decisions about your sexual health.
Read more: STD vs STI | HIV vs AIDS | Viral load logs
Frequently Asked Questions
What does NAAT stand for?
Nucleic acid amplification test — the standard method for detecting chlamydia, gonorrhoea and other infections.
What does U=U mean?
Undetectable = Untransmittable — a person with HIV on effective treatment cannot pass it on sexually.
What’s the difference between STI and STD?
STI (infection) is the preferred term; STD (disease) is older and less accurate.
Related reading
- Alcohol and HIV: What You Need to Know
- Anxiety and HIV: Coping and Getting Support
- Are All STIs Curable?
- Blood Problems and HIV: Anaemia, Low Platelets and More
- Can HIV Be Cured? Where the Science Stands
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
