This ED glossary explains the medical terms you’re likely to encounter researching erectile dysfunction, in plain language, with a link to the full article wherever one exists on this site. Twenty-five essential terms, organised alphabetically.
A
Alprostadil — the medication most commonly used in penile injection therapy, working by directly relaxing the smooth muscle inside the penis.
C
Corpus cavernosum — the paired chambers of erectile tissue inside the penis that fill with blood during an erection.
Circumcision — surgical removal of the foreskin; its relationship to erectile function is genuinely contested in the research, see our circumcision and ED guide.
D
Diabetic neuropathy — nerve damage caused by prolonged high blood sugar, one of the mechanisms behind diabetes-related ED.
E
Endothelial dysfunction — impaired function of the thin inner lining of blood vessels, reducing their ability to relax and widen during arousal; a shared mechanism behind many physical causes of ED covered throughout this site.
Erectile dysfunction (ED) — the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual activity, generally for three months or more.
H
HbA1c — a blood test measuring average blood sugar over roughly three months, used to screen for diabetes as part of a proper ED assessment.
Hypogonadism — clinically confirmed low testosterone, diagnosed through repeated morning blood tests alongside symptoms, see our low testosterone guide.
I
IIEF-5 — the International Index of Erectile Function (short form), a validated five-question clinical questionnaire doctors use to score ED severity.
Intracavernosal injection — see Penile injection therapy.
N
Neurogenic ED — erectile dysfunction caused by damage or disruption to the nerve pathways involved in arousal, from conditions like diabetes, spinal cord injury, or MS, see our guide to complete inability to get hard.
Nitric oxide — the chemical signal that tells penile blood vessels to relax and widen during arousal; PDE5 inhibitors work by prolonging its effect.
Nocturnal penile tumescence (NPT) — erections that occur during sleep, generally during REM sleep, whose presence or absence is a useful diagnostic clue, see our morning erections guide.
O
OPIAD — opioid-induced androgen deficiency, a recognised syndrome where long-term opioid use suppresses natural testosterone production, see our opioids and ED guide.
P
PDE5 inhibitor — the class of prescription medicine including sildenafil and tadalafil, see our PDE5 inhibitors guide.
Penile injection therapy — a treatment using a medication injected directly into the penis, see our dedicated guide.
Peyronie’s disease — a connective tissue disorder causing curvature, pain or deformity of the penis, frequently co-occurring with ED, see our dedicated guide.
Post-Finasteride Syndrome (PFS) — a genuinely contested condition describing persistent sexual and other side effects some men report after stopping finasteride, see our finasteride guide.
Priapism — a painful erection lasting more than four hours; a genuine medical emergency requiring urgent treatment.
Primary ED — erectile dysfunction present since a man’s first attempts at sexual activity, distinct from secondary ED.
Prostatectomy — surgical removal of the prostate, most often for prostate cancer, see our prostate and ED guide.
PSA (Prostate-Specific Antigen) — a blood test used in prostate cancer screening.
R
Reflexogenic erection — an erection triggered by direct physical touch, controlled by nerves in the lowest part of the spinal cord, distinct from a psychogenic erection, see our spinal cord injury guide.
S
Secondary ED — erectile dysfunction that develops after a period of previously normal function, the more common pattern.
SSRI — a class of antidepressant medication with a well-documented link to sexual side effects, see our antidepressants and ED guide.
T
Testosterone (total vs free) — total testosterone measures all testosterone in the blood; free testosterone measures only the portion not bound to proteins and available for the body to use, sometimes tested separately in borderline cases.
TRT — testosterone replacement therapy, a prescription treatment for confirmed hypogonadism, see our dedicated guide.
V
Vacuum erection device (VED) — a mechanical device using negative pressure to draw blood into the penis, see our dedicated guide.
Vasculogenic ED — erectile dysfunction caused by impaired blood flow, the most common category overall, covered throughout our causes cluster.
Venous leak — a condition where veins fail to properly trap blood in the penis, causing an erection to fade despite normal initial blood flow, see our guide to difficulty maintaining an erection.
Frequently Asked Questions | ED Glossary
Why does terminology matter when researching ED?
Understanding the actual terms helps you ask better questions at your consultation and make sense of test results or treatment options without confusion.
Do I need to know all these terms before booking a consultation?
Not at all, this is a reference to use as needed, we’ll explain anything relevant to your specific situation clearly during your consultation regardless.
Is a term missing that I’ve come across elsewhere?
Get in touch and let us know, we’re happy to expand this glossary over time.
Are these definitions medical advice?
No, they’re general educational definitions. Your specific situation should always be discussed with a qualified practitioner.
Why do some terms link to full articles and others don’t?
Terms with a dedicated deep-dive article on this site are linked directly; more general terms are defined here without a separate page.
Is this glossary South Africa-specific?
The medical terminology itself is universal; see our South Africa statistics guide for the local data context alongside these definitions.
Reviewed by George Mulaudzi, Naturopath, Erectile Dysfunction Clinic. This glossary provides general educational definitions and is not a substitute for personalised medical advice.
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