Glossary
Short, clear definitions from A to Z — quickly learn the term you are curious about.
B
Balance Sheet
A balance sheet is a fundamental financial statement showing a company's assets, liabilities and equity at a specific date. Based on the equation "Assets = Liabilities + Equity," it provides a snapshot of the firm's financial position at that moment; unlike an income statement, it reflects a single point in time rather than a period.
Bronze Age
The Bronze Age is the prehistoric period, dated roughly to 3300–1200 BCE, during which humanity began the widespread use of bronze, an alloy of copper and tin. City-states, writing systems and long-distance trade networks developed in this era, and major civilizations such as the Hittites and Ancient Egypt reached the height of their power.
E
Elenchus
Elenchus is the philosophical method of refutation used by Socrates in his dialogues, in which questioning exposes the contradictions in a person's stated view, prompting them to examine and revise their thinking. Central to the Socratic method, elenchus aims not to impart knowledge directly but to lead the interlocutor to recognize inconsistencies in their own reasoning.
Etymology
Etymology is the branch of linguistics that studies the origin of words, the phonetic and semantic changes they have undergone over time, and the routes by which they have passed from one language to another. It traces words primarily through written sources, comparative linguistic analysis and the rules of historical sound change.
Exoplanet
An exoplanet is a planet that orbits a star outside the Solar System. First confirmed in the 1990s, such planets are very difficult to observe directly and are usually detected by indirect methods, such as periodic dimming of a star's light or gravitational wobbles.
Extremophile
An extremophile is any organism able to survive and even thrive in conditions — extreme temperature, pressure, radiation, salinity or drought — that would be lethal to most forms of life. Tardigrades, certain bacteria and deep-sea creatures are examples; the survival mechanisms of such organisms offer astrobiologists clues about where to look for life beyond Earth.
G
Gene Editing
Gene editing is the general name for biotechnological methods that allow targeted changes to be made to an organism's DNA sequence — including cutting, deleting, inserting or altering a specific gene. With the development of tools such as CRISPR-Cas9, these procedures have become far faster, cheaper and more precise than before, and are now widely used in agriculture, medicine and basic biological research.
Guinness World Records
Guinness World Records is a reference book that documents and annually publishes human achievements, natural phenomena and objective records from around the world. It originated in 1955, inspired by an unresolved argument during a hunting trip taken by Sir Hugh Beaver, managing director of the Guinness Brewery, over which was Europe's fastest game bird.
H
Habeas Corpus
Habeas corpus, Latin for "that you have the body," is a legal safeguard that allows a court to review whether a person is being unlawfully detained. With roots reaching back to 13th-century England and the Magna Carta, it is regarded in modern legal systems as one of the most fundamental protections of personal liberty.
Hieroglyphs
Hieroglyphs are a picture-based writing system used in Ancient Egypt that could represent both sounds and concepts. Undeciphered for thousands of years, the script was finally decoded in 1822 by Jean-François Champollion, thanks to the Rosetta Stone discovered in 1799, which bore the same text in three different scripts (hieroglyphic, demotic and ancient Greek).
I
Immune System
The immune system is a complex defensive network of cells, tissues and organs that protects the body against bacteria, viruses and other harmful microorganisms. It consists of two main components: innate immunity (fast but non-specific) and adaptive immunity (slower to develop but with target-specific memory); many dietary and lifestyle factors directly affect its effectiveness.
Impressionism
Impressionism is an art movement that emerged in France in the 1870s, aiming to capture on canvas not the precise outlines of objects but the impression of light and of the fleeting moment, using rapid, visible brushstrokes. Rejected by the official art institutions of its time, this approach eventually became one of the most influential turning points in modern art.
Internal Combustion Engine
An internal combustion engine is an engine that converts into mechanical motion the energy released when fuel (usually gasoline or diesel) is mixed with air and burned inside an enclosed combustion chamber. It has been the dominant power source for road transport since the late 19th century and remains in use today in hybrid systems that combine it with electric motors.
M
Magnetoreception
Magnetoreception is the ability of certain animal species to sense the Earth's magnetic field in order to navigate, migrate or determine their position. Observed in migratory birds, sea turtles and some fish, this sense is thought to rely on biophysical mechanisms that are still not fully understood.
Marathon
The marathon is a long-distance running race in athletics covering 42.195 kilometres. It takes its name from the legend of the ancient Greek messenger Pheidippides, said to have run to Athens in 490 BCE to announce the victory at the Battle of Marathon; it has been contested regularly at the modern Olympic Games since 1896.
Mediterranean Diet
The Mediterranean diet is a dietary pattern based on the traditional eating habits of countries bordering the Mediterranean, such as Greece, Italy and Spain, emphasizing abundant vegetables, fruit, whole grains, legumes and olive oil, with limited consumption of red meat and processed foods. Linked by decades of scientific research to heart health and longevity, it is regarded as a holistic way of life.
Metacognition
Metacognition is a person's awareness of their own thinking and learning processes, together with the ability to monitor and regulate them — often described simply as "thinking about thinking."
Metonic Cycle
The Metonic cycle is an astronomical period based on the fact that 19 solar years correspond almost exactly to 235 lunar months (cycles of the Moon's phases). Thanks to this alignment, lunisolar calendar systems (such as the Hebrew calendar) that seek to keep lunar and solar reckoning in step insert an additional month in certain years to synchronize the seasons with the lunar phases.
Microbiology
Microbiology is the branch of biology that studies the structure, function and interactions of microorganisms invisible to the naked eye, such as bacteria, viruses, fungi and parasites. It has wide-ranging applications in medicine, food safety, agriculture and environmental science, from diagnosing diseases to monitoring antibiotic resistance.
Modern Design
Modern design is a design philosophy that emerged in the early 20th century, foregrounding functionality, simplicity and unornamented geometric forms, and grounded in the principle that "form follows function." The Bauhaus school played a pioneering role in systematically teaching and disseminating this approach in architecture, furniture and industrial design.
MRNA Vaccine
mRNA (messenger RNA) is a single-stranded RNA molecule that carries genetic information encoded in the DNA of the cell nucleus to the ribosomes, where proteins are made. mRNA vaccines instruct the body's own cells to temporarily produce a specific protein (for example, a virus's surface protein), thereby training the immune system to recognize it.
N
Nabataeans
The Nabataeans were an ancient Arab people who flourished from the 4th century BCE to the 1st century CE in what is today Jordan, southern Israel and northern Arabia, and who carved their capital, Petra, out of rock. Situated at the crossroads of caravan trade routes, they amassed great wealth especially through the incense and spice trade.
Nucleosynthesis
Nucleosynthesis is the process by which atomic nuclei combine (fusion) or split (fission) to form new, heavier elements. Occurring continuously in the cores of stars, this process accelerates during extremely energetic events such as supernova explosions, giving rise to elements heavier than iron — such as gold and uranium — in the universe.
P
PISA
PISA (Programme for International Student Assessment) is an international assessment organized every three years by the OECD that comparatively measures the competencies of 15-year-old students worldwide in reading, mathematics and science. Its results are frequently used as a reference point when countries review their education policies.
Plate Tectonics
Plate tectonics is the geological theory explaining that the Earth's outermost layer (the lithosphere) is divided into plates of various sizes that move slowly over the mantle. The collision, separation or sliding past of these plates accounts for large-scale features such as mountain building, earthquakes, volcanic activity and ocean trenches.
Principle Of Reciprocity
The principle of reciprocity is an ethical precept holding that one should treat others as one would wish to be treated. Also known as the "Golden Rule," it appears in various forms in nearly all major religious and philosophical traditions and is regarded as a cornerstone of moral conduct grounded in mutual respect.
Probiotic
Probiotics are live microorganisms that, when consumed in sufficient amounts, have been scientifically shown to benefit the host by supporting the gut microbiome. They occur naturally in fermented foods such as yogurt, kefir, kombucha and pickles, and can also be taken as supplements in capsule or powder form. Their effects vary by species and strain — so "probiotic" is not a single substance but a broad category encompassing many different bacteria and yeasts.
Purchasing Power Parity
Purchasing power parity (PPP) is an economic measurement method that compares currencies of different countries according to how much of the same basket of goods and services they can buy. Unlike market exchange rates, it accounts for differences in the cost of living, and is therefore considered to give a more realistic picture than raw exchange rates when comparing countries' true economic size or standard of living.
R
Relative Humidity
Relative humidity is the amount of water vapor present in the air expressed as a percentage of the maximum amount the air can hold at that temperature. Relative humidity levels above 60% tend to create conditions favorable to mold and fungal growth in indoor spaces.
Right To A Fair Trial
The right to a fair trial is a fundamental human right guaranteeing that a person is tried before an independent and impartial court, within a reasonable time, and with the opportunity to defend themselves. The presumption of innocence, the principle of equality of arms, and the inadmissibility of unlawfully obtained evidence are among its core components.
S
Soda Lake
A soda lake is a lake in an endorheic (closed) basin where evaporation exceeds water inflow, causing carbonate and bicarbonate salts to become concentrated and the water to turn alkaline. The pH of such lakes is typically between 9 and 12, and they host only specialized microorganisms and species adapted to these extreme conditions.
Strange Situation Procedure
The Strange Situation Procedure is a standardized laboratory experiment designed by developmental psychologist Mary Ainsworth in the 1970s to determine an infant's attachment style by observing its reactions when briefly separated from its parent and left with a stranger. The experiment was used to define the main attachment categories, such as secure, avoidant and anxious-resistant.
Sustainability
Sustainability is an approach that seeks to meet present needs without compromising the ability of future generations to meet their own. Encompassing environmental, economic and social dimensions together, the concept provides the underlying rationale for many everyday and industrial practices, from composting to renewable energy.
V
VAR
VAR (Video Assistant Referee) is a technology and officiating system that supports the on-field referee through video footage in critical decisions such as goals, penalties, direct red cards and mistaken identity. It was incorporated into the official Laws of the Game by IFAB in 2018 and has since been widely used in professional football.
Volcanic Tuff
Volcanic tuff is a porous, soft sedimentary rock formed when ash, pumice and rock fragments ejected during a volcanic eruption compact and harden over time. Because it is far easier to carve than other rocks, it has allowed underground cities and dwellings to be hewn out for centuries in regions such as Cappadocia.