Science Vocabulary in English

IELTS Academic reading and writing tasks regularly draw on texts from biology, chemistry, physics, and environmental science. Knowing words like hypothesis, variable, and evidence allows you to understand source texts more accurately and write Task 1 and Task 2 responses that sound appropriately academic. Without this vocabulary, even a strong grasp of grammar can leave your writing vague or imprecise.

In scientific English, a hypothesis is a testable prediction made before an experiment is carried out, while a theory is a well-supported explanation backed by substantial evidence collected over time. Mixing the two is a common error in learner writing. In everyday English, "theory" is often used loosely to mean a guess, but in academic contexts this usage is considered imprecise.

Think of it as a hierarchy: an atom is the smallest particle of a single element; a molecule is two or more atoms bonded together (they can be the same element, like O₂, or different ones); and a compound is specifically a molecule made of two or more different elements. Visualising the scale — atom inside molecule inside compound — makes the distinction stick quickly.

Yes. In everyday English, cell most commonly refers to a prison cell or a mobile phone cell. In biology, it means the smallest structural and functional unit of a living organism. When reading scientific texts, always check the context: if the surrounding words include membrane, nucleus, or divide, the biological meaning applies.

The most common collocations are: conduct an experiment, carry out an experiment, run an experiment, and design an experiment. You would rarely say "make an experiment" in academic English, even though learners from several language backgrounds translate it that way. Practising these fixed phrases alongside the word itself is far more effective than studying definitions alone.

Both words describe how fast something moves, but velocity includes a direction, making it a vector quantity, while speed is a scalar with no direction. In physics writing this distinction is critical: a car travelling at 60 km/h has a speed, but travelling at 60 km/h due north has a velocity. In casual English, the two words are often treated as synonyms, but academic science writing requires precision.

Yes. Although radiation is often associated with nuclear hazards, the word simply describes energy emitted as waves or particles. Sunlight is a form of radiation, and medical X-rays, microwave ovens, and MRI machines all involve radiation used beneficially. IELTS and academic texts often discuss radiation in neutral or positive contexts, so treating it as purely negative can lead to misreading a passage.

Many long science words are built from Greek and Latin roots, which makes them easier to decode once you spot the pattern. Photo- means light, and synthesis means putting together — so photosynthesis literally means "putting together using light." Learning a handful of common roots (bio-, thermo-, geo-, micro-) can help you unlock dozens of science words without memorising each one from scratch.

Focus on the words that appear most frequently in general academic writing rather than highly specialised technical terms. Words like evidence, observation, evolution, and energy appear across subjects including economics, history, and social studies. Using flash cards, gap-fill exercises, and reading short science news articles are all effective strategies that do not require a scientific background.

More than most learners expect. Words like energy, reaction, element, and gravity are used daily in conversation, often metaphorically: "She brought great energy to the meeting," or "His reaction was unexpected." Understanding both the precise scientific meaning and the metaphorical usage gives you a richer command of the language and helps you sound natural in a wider range of situations.