ISTQB Glossary 2026 — 870+ testing terms, organised by syllabus chapter

A glossary is only useful if it teaches you something a dictionary lookup would not. That is the whole design principle behind this one. Instead of 872 near-identical definition stubs, the ISTQB vocabulary here is consolidated into eight chapter guides that follow the CTFL v4.0 syllabus, the Agile Tester extension and the advanced specialist modules. Each chapter reads as one continuous study session: an original commentary on what the chapter is really testing, then every term in it with the official ISTQB definition quoted and attributed, our own plain-English reading, and a concrete example from delivery work — a code snippet, a pipeline step, or a short scenario from a real sprint.

How to use this glossary

If you are studying for the exam, work chapter by chapter rather than alphabetically. The syllabus builds a vocabulary in layers: Chapter 1 fixes the meaning of error, defect and failure, and Chapters 2 through 6 are written using those words. Reading Chapter 6 first means guessing at half the sentences. Take one chapter page, read the intro, skim every term in the sticky sidebar, then go back and read carefully only the terms you could not define out loud. That second pass is where the marks are.

If you are here from an interview prep list or a job description, use the A–Z index below. Type the term into the search box, jump to its chapter page, and read it in context with the four or five terms that sit next to it. Interviewers rarely ask "define regression testing" in isolation; they ask how you decide what to re-run after a fix, which is a question about confirmation testing, regression testing, risk and test selection all at once. The chapter layout puts those neighbours on the same page on purpose.

If you are here mid-sprint because a colleague used a term you did not want to question in stand-up, search it, read the plain-English line and the example, and move on. Every term has a stable anchor URL, so you can paste the exact link into a pull request or a Slack thread.

What is in each chapter

Chapters 1 to 6 mirror the CTFL v4.0 syllabus: fundamentals, testing throughout the SDLC, static testing, test analysis and design, managing the test activities, and test tools. Two extra pages go beyond Foundation level. The agile page covers the Agile Tester extension — user stories, the whole-team approach, the test pyramid and agile metrics. The advanced page collects the specialist vocabulary for performance, security, usability and accessibility, mobile and IoT, cloud and data, and AI and machine-learning testing. You will not be examined on that last page at Foundation level, but it is where most senior QA and SDET job descriptions get their language.

A note on sourcing, because it matters: ISTQB definitions are quoted verbatim and clearly attributed in a blockquote on every entry. Everything outside that blockquote — the explanations, examples, exam tips and chapter commentary — is written by our own QA engineers based on project work, and is reviewed before publication. ISTQB® is a registered trademark of the International Software Testing Qualifications Board; SoftwareTestPilot is not affiliated with or endorsed by the ISTQB.

When you can define the terms, the next step is answering questions under time pressure. The free ISTQB Foundation mock test gives you 40 CTFL v4.0 questions on a 60-minute timer with a chapter-wise score breakdown, and the syllabus guide shows how the marks are distributed across chapters so you know where the revision time is worth spending.