#system

• Aeronautical — Belonging to aeronautics or relating to aerial navigation, as well as the study, design, construction, and operation of aircraft. This term describes structural, regulatory, industrial, or scientific elements essential for vehicle flight within Earth's atmosphere, ranging from airplanes and helicopters to complex propulsion and control systems.
• Air navigation — The science, technology, or practical activity of guiding an aircraft safely along a determined route between two specific geographic points. This complex field includes trajectory planning, exact position determination through astronomical, radio, or satellite methods, as well as constant interaction with air traffic management systems and meteorological services.
• Aeroplankton — The totality of microscopic or very small living organisms (bacteria, spores, pollen, protozoa, unicellular algae, and small insects) that drift passively in the atmosphere, carried by air currents. Similar to aquatic plankton, this biological collective forms the trophic baseline of aerobiology and represents a critical indicator for the ecological purity of atmospheric layers.
• Jet engine — An air-breathing jet engine (reactive) that utilizes surrounding air as an oxidizer for burning fuel and generating propulsion force through the rapid expulsion of exhaust gases. Unlike rocket engines, this structural mechanical assembly fully depends on the presence of Earth's atmosphere to function, being widely used in modern airliners and supersonic aircraft.
• Aerostatics — A branch of fluid mechanics and physics that studies the equilibrium conditions of air and other gases, as well as of solid bodies immersed within them. In an applied sense, it represents the science, technology, and history of designing, constructing, and navigating lighter-than-air aircraft, grounded in hydrostatic laws transposed to the atmospheric environment.
• Aeroterrestrial — Belonging or relating simultaneously to the air and the earth, or performing its specific activity or phenomena within both the aerial and terrestrial environments. In biology, it describes a complex biotope or species relying on soil for shelter and the atmosphere for respiration or movement. In logistics, it applies to mixed transport systems combining air and road routes.
• Afocal — Having no real focal point or a finite focal length; relating to an optical system configured so that light rays entering parallel also exit parallel. In applied optics, these systems modify beam diameter or visual angle without focusing light onto a screen.
• Aftidor — Proprietary commercial name of a phytosanitary product widely used in agriculture, formulated as a highly efficient systemic insecticide. Its active substance acts through contact and ingestion against a broad spectrum of pests attacking vegetable, fruit tree, or cereal crops, protecting the cellular structure of treated plants.
• Aphthosis — A pathological condition characterized by the appearance of repeated, chronic, or generalized eruptive outbreaks of aphthae on the oral or genital mucosa. It represents a dermatological and stomatological disorder that can be linked to immune imbalances, hereditary factors, or severe episodes of emotional stress.
• Agalactia — A pathological condition characterized by the complete absence of milk secretion in the mother (human or female mammals) after childbirth. This structural and functional disorder can be caused by severe endocrine dysfunctions, malformations of the mammary glands, intense febrile states, strong emotional stress, or malnutrition.
• Agathosma — A genus of small to medium-sized evergreen shrubs in the family Rutaceae, endemic to the Mediterranean-climate regions of South Africa, particularly the Western Cape province. These shrubs are highly recognized for their ericoid, aromatic leaves heavily dotted with oil glands that release a strong, pleasant, or medicinal scent when crushed, holding substantial ecological importance within the fynbos ecosystem alongside unique ornamental and therapeutic values.
• Archaic aid — An archaic form of Slavic or Hungarian origin used in the past to denote material aid, financial support granted to a community, or a special fee collected within the feudal administrative system. In old legal and administrative documents, the term referred to structural contributions or regulated assistance owed to local or princely courts.
• Agorot — The plural noun form of agorot; it refers to the fractional currency unit of Israel, representing exactly one-hundredth part of an Israeli New Shekel (ILS). Coins minted in agorot denominations are actively circulated for retail and governmental transactions.
• Agrarian — Relating to land ownership, soil cultivation, agricultural production, or the social and economic structure of rural areas; pertaining to farming or the legal regime of landed property. Historically, it describes policies, laws, or reforms aimed at land redistribution.
• Agrarian — The feminine form of the term agrar; relating to land ownership, farming tasks, agricultural laws, or rural social structures. Frequently used in crucial historical and economic collocations such as land reform.
• Agro-ameliorative — Serving to improve the physical, chemical, or biological properties of degraded or productive soils to increase agricultural crop yields. The term describes complex structural measures, works, or techniques, such as drainage, irrigation, application of soil amendments, or planting protective shelterbelts.
• Agrobiocenosis — A biotic community within an agricultural ecosystem (agroecosystem), created and partially controlled by humans, consisting of cultivated crops, weeds, beneficial or pest insects, soil microorganisms, and associated animals. Unlike a natural biocenosis, it exhibits low structural stability, limited genetic diversity, and requires constant external energy inputs.
• Agrocenosis — An artificial biocenosis created and directly controlled by humans through agricultural activities, represented by the community of cultivated plants, animals, insects, and microorganisms within an agricultural ecosystem. Unlike natural ecosystems, it features low biological diversity, fragile ecological stability, and depends entirely on human intervention to maintain balance and achieve productivity.
• Agroecology — A scientific discipline that studies ecological processes applied to agricultural production systems, integrating principles from ecology, agronomy, and social sciences. This field promotes the sustainable management of agroecosystems by optimizing interactions between plants, animals, humans, and the environment, offering viable alternatives to intensive industrial agriculture.
• Agroecosystem — An ecosystem intentionally modified, shaped, and controlled by humans through agricultural activities for the purpose of obtaining plant or animal biomass. It integrates local biotic components with technological and anthropic elements, being characterized by a partially directed energy flow, open nutrient cycles, and a structural stability dependent on external energy and economic inputs.