Word library
8,130 words, searchable by word, definition, part of speech, and CEFR level.
Relating to the nucleus of an atom, especially the energy released when it is split or joined, or relating to nuclear weapons.
The splitting of a heavy atomic nucleus into two lighter nuclei, releasing a large amount of energy.
The combining of two light atomic nuclei into a heavier one, releasing enormous energy, the same process that powers the sun.
One of the small building-block molecules that link together to form a strand of DNA or RNA.
The central part of a cell that contains most of its genetic material, or the dense center of an atom.
In statistics, the default assumption that there is no real effect or difference, which a study tries to gather evidence against.
A word or symbol used to count or show an amount.
The number above the line in a fraction, showing how many parts of the whole are being counted.
The ability to understand, interpret, and work with numerical information to solve problems.
Information expressed in the form of numbers rather than words or categories.
Existing in large numbers; many.
A person trained to care for sick or injured people, often working alongside doctors.
To care for and encourage the growth or development of someone or something.
A hard-shelled fruit or seed with an edible part inside.
A substance that provides nourishment needed for growth and health.
Substances that living things need to grow and stay healthy, found in food or soil.
The process of taking in and using food for health and growth.
A strong, artificial fabric or material used to make clothing, rope, and other products.
Used after a number to state the time.
A large, strong tree that produces acorns and can live for hundreds of years.
A fertile area with water in the middle of a desert, or a peaceful place amid difficulty.
A type of grain often eaten as porridge or used in baking.
A solemn formal promise, often invoking something sacred, that one will tell the truth or fulfill a duty.
The grain of a cereal plant, often rolled or crushed and cooked to make porridge.
Stubbornly refusing to change your mind or attitude.
To do what someone tells you to do, or to follow a rule.
To make something unclear or difficult to understand, often deliberately.
A thing that can be seen and touched but is not alive.
The act of treating a person as an object, especially by valuing them only for their appearance or usefulness rather than as a full human being.
A statement or feeling of disagreement or disapproval about something.
Based on facts rather than personal feelings or opinions.
In an optimization problem, the specific quantity that a model is trying to maximize or minimize.
The lens on a microscope or telescope closest to the object being viewed, which gathers light and forms the first magnified image.
The quality of presenting information fairly, based on facts, without letting personal feelings or opinions shape it.
A duty to do something, especially because of a law, promise, or moral responsibility.
Slanting or sloping, rather than straight or direct, or indirect in the way something is expressed.
Not aware of what is happening around you.
Not well known, or difficult to understand because it isn't clearly expressed.
Excessively eager to please or obey someone, in a way that seems insincere.
The act of watching something carefully, or a comment based on what you have noticed.
A building equipped with telescopes for studying stars, planets, and weather.
To watch someone or something carefully, especially to learn something from it.
No longer used because something newer and better has replaced it.
Something that blocks progress or makes it harder to achieve a goal.
Refusing to change an opinion or course of action despite good reasons to do so.
Noisy, unruly, and difficult to control.
Something that blocks a path, process, or view.
To get or acquire something, often through effort or a formal process.