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Clinical Trial & Research Glossary
Clear, plain-language definitions to help you navigate clinical research with confidence — without a medical dictionary at your side.
Trial listings and consent forms are full of words that can feel like a different language. Here are the ones that come up most often, explained simply. Search or filter by category below — and remember your study team and the trial's consent documents are always the authoritative source for any specific study.
Often misunderstood
Clinical Trial
Not just "experimental"
It can sound risky or purely experimental — but trials run under heavy safety oversight and regulation, with consent and monitoring throughout.
Placebo
Not "no treatment"
Often assumed to mean nothing at all. In reality many trials compare a new treatment to the current standard of care — not to nothing.
Phase 1
Not "unsafe"
Assumed to be dangerous. Phase 1 is a structured, closely watched step focused on safety and finding the right dose.
Eligibility
Not a simple yes/no
It's detailed and reviewed by the study team — even a "recruiting" trial still has rules about who can join.
Randomization
Not a gamble
It can feel unfair, but assigning groups by chance keeps them comparable so the result is trustworthy.
Standard of Care
Not "the best possible"
Confused with the newest or best option. It means the typical, evidence-based treatment for your condition.
A–Z glossary
32 terms
- Active, Not RecruitingTrial basics
- The study is ongoing but is no longer enrolling new participants. Enrolled participants are still being followed and may still receive study treatment, but new people cannot join.
- Related: Recruiting · Not Yet Recruiting
- Am I guaranteed to qualify?Common concerns
- No — final eligibility is always determined by the study team after review. Matching tools can show studies that may fit, but the research team makes the final decision after reviewing your details and records.
- Related: Eligibility Criteria · Trial Matching
- BiomarkerTreatment & medical
- A measurable biological feature that may help guide treatment decisions — for example a gene mutation, a protein level, or another marker in blood or tissue. Biomarkers can help match a person to treatments most likely to help them.
- Related: Targeted Therapy
- Clinical TrialTrial basics
- A research study that tests new ways to prevent, detect, or treat a disease. Trials may study new medicines, procedures, devices, or combinations of treatments. They follow a written plan (a protocol) and are overseen by ethics boards and regulators to protect participants.
- Related: Study Phase · Eligibility Criteria · Sponsor
- CompensationLocation & logistics
- Payment or reimbursement for participation, which may include travel costs. Compensation varies by study and may cover time, travel, parking, or lodging. It is described in the informed-consent documents.
- Related: Informed Consent · Study Site
- Control GroupTreatment & medical
- The group in a study that receives standard treatment or placebo for comparison. Comparing the study treatment against a control group helps researchers tell whether a new approach truly makes a difference.
- Related: Randomization · Placebo · Standard of Care
- De-identified DataPrivacy & safety
- Information that has been stripped of personal identifiers. Names, contact details, and other identifying information are removed so the data cannot be easily traced back to a specific person.
- Related: HIPAA · Informed Consent
- Does joining a trial mean I'm a test subject?Common concerns
- Clinical trials follow strict ethical and safety regulations to protect participants. Trials are reviewed by ethics boards, require informed consent, and are monitored throughout. Participants keep the right to ask questions and to withdraw at any time.
- Related: Informed Consent · Clinical Trial
- EHR (Electronic Health Record)Matching & search
- A digital version of a patient's medical record that brings together diagnoses, medications, lab results, and visit history in one place that can be shared between clinicians.
- Related: ICD-10 Code
- Eligibility CriteriaTrial basics
- The rules that determine who can or cannot participate in a study — age, diagnosis, stage of disease, prior treatments, lab values, and more. Eligibility is not simply yes/no; it is reviewed in detail by the study team.
- Related: Inclusion Criteria · Exclusion Criteria
- Exclusion CriteriaTrial basics
- Factors that prevent someone from joining a study. They exist to keep participants safe and to keep results clear — for example, certain other conditions or medications.
- Related: Inclusion Criteria · Eligibility Criteria
- Experimental TreatmentTreatment & medical
- A treatment still being studied that has not yet been approved for general use. Also called investigational treatment — "investigational" means "still being studied," not "unsafe."
- Related: Standard of Care · Clinical Trial
- HIPAAPrivacy & safety
- A U.S. law that protects the privacy and security of health information. HIPAA sets rules for how certain organizations may use and share your health information, and gives you rights over your own records.
- Related: De-identified Data · Informed Consent
- ICD-10 CodeMatching & search
- A standardized medical code used to classify diagnoses. ICD-10 codes give each diagnosis a consistent label so records and trial criteria can be compared reliably.
- Related: EHR (Electronic Health Record) · Trial Matching
- ImmunotherapyTreatment & medical
- Treatment that helps the immune system fight disease. It works with the body's own defenses rather than attacking disease directly, and is used for several cancers and other conditions.
- Related: Targeted Therapy · Biomarker
- Inclusion CriteriaTrial basics
- Requirements you must meet to join a study. They define the group a trial is designed to study, such as a specific diagnosis, age range, or disease stage.
- Related: Exclusion Criteria · Eligibility Criteria
- Informed ConsentPrivacy & safety
- The process where participants learn about a study's risks and benefits before agreeing to join. Informed consent is a rights process, not just paperwork — you can ask questions, take your time, and leave a study at any point for any reason.
- Related: Clinical Trial · Compensation
- Not Yet RecruitingTrial basics
- A trial that has been approved but has not started enrolling participants yet. It is planned and registered, but the team is not accepting participants at this moment. This status often changes to "Recruiting."
- Related: Recruiting · Active, Not Recruiting
- PlaceboTreatment & medical
- An inactive substance designed to look like the treatment being tested. Not all trials use placebos — many compare a new treatment to the current standard of care rather than to nothing at all. A placebo is not the same as "no treatment."
- Related: Control Group · Randomization · Standard of Care
- Preference-Enhanced MatchingMatching & search
- ClinicalMatchMate's feature that considers patient preferences alongside eligibility. Beyond medical eligibility, it weighs preferences such as travel distance or remote participation, so results fit your real life — not just the criteria on paper.
- Related: Trial Matching · Travel Radius
- Principal Investigator (PI)Trial basics
- The lead researcher responsible for the trial at a specific study location. The PI oversees the conduct of the study at their site, including participant safety and following the protocol.
- Related: Sponsor · Study Site
- RandomizationTreatment & medical
- A process that assigns participants to treatment groups by chance. Randomization helps make the groups comparable and keeps the results fair, so the trial measures the treatment rather than other differences between people.
- Related: Control Group · Placebo
- RecruitingTrial basics
- A trial that is currently looking for participants. Recruiting means the study is open to enrollment — but eligibility rules still apply, so it is not open to everyone.
- Related: Not Yet Recruiting · Eligibility Criteria
- Remote TrialLocation & logistics
- A study that allows some or all visits to happen virtually. Also called a decentralized trial — it may use telehealth visits, local labs, home nursing, or shipped medication to reduce travel.
- Related: Study Site · Travel Radius
- SponsorTrial basics
- The organization responsible for running and funding a clinical trial. A sponsor may be a pharmaceutical company, academic center, nonprofit, or government agency.
- Related: Principal Investigator (PI) · Clinical Trial
- Standard of CareTreatment & medical
- The usual treatment recommended by doctors based on current evidence — the typical, evidence-based treatment for a condition, not necessarily the newest or only option.
- Related: Experimental Treatment · Study Phase
- Study PhaseTrial basics
- The stage of testing a trial is in — Phase 1, 2, 3, or 4. Phase 1 focuses on safety and dosing in a small group; Phase 2 looks at whether a treatment works and continues safety checks; Phase 3 compares it to standard care in larger groups; Phase 4 follows approved treatments over time.
- Related: Clinical Trial · Standard of Care
- Study SiteLocation & logistics
- The hospital, clinic, or medical center where the trial takes place. A single trial may run at many sites, each with its own research team led by a principal investigator.
- Related: Principal Investigator (PI) · Remote Trial
- Targeted TherapyTreatment & medical
- Treatment that focuses on specific genetic or molecular features of a disease. Targeted therapies act on particular changes in cells — often identified by a biomarker — rather than affecting the whole body the way some older treatments do.
- Related: Biomarker · Immunotherapy
- Travel RadiusLocation & logistics
- The distance a participant is willing or able to travel to take part in a trial. ClinicalMatchMate uses your travel radius as a preference so that matches respect how far you can realistically go.
- Related: Remote Trial · Preference-Enhanced Matching
- Trial MatchingMatching & search
- Comparing a person's medical details with trial eligibility criteria to find relevant studies. Matching surfaces studies that may be relevant based on public trial information. It does not confirm eligibility — only the study team can do that.
- Related: Eligibility Criteria · Preference-Enhanced Matching
- Warm TransferMatching & search
- Immediate connection to a research coordinator after a participant expresses interest. Instead of a dead end, a warm transfer hands you off directly to the study team so your questions get answered by the people running the trial.
- Related: Trial Matching · Principal Investigator (PI)
Sources
- GovernmentClinicalTrials.gov — Glossary of Common Site Terms
- GovernmentNCI Dictionary of Cancer Terms
- GovernmentClinical Trials: What Patients Need to Know (FDA)
- GovernmentNIH Clinical Research Trials and You
- GovernmentHIPAA for Individuals (HHS)
- GovernmentICD-10-CM (CDC / NCHS)
- GovernmentWhat is an Electronic Health Record? (HealthIT.gov)
Last reviewed 2026-06-03 · James Mbualungu, MD/MBA candidate · Content v1.0