#activ

• Aero club — A sports association, club, or aeronautical organization aimed at promoting, practicing, and developing recreational flight activities, piloting, skydiving, gliding, or aeromodelling. The term also designates the material base of such an association, including the airfield, hangars, aircraft, and training facilities.
• Boost-glider model — An experimental mockup or small-scale model of a hybrid aerospace vehicle, structurally designed to combine the aerodynamic characteristics of an aircraft (wings, gliding flight) with the reactive propulsion force specific to a rocket. This type of model is used in aeromodelling and rocketmodelling competitions to study dynamic behavior during vertical launch and controlled return phases.
• Air-breathing jet — Utilizing the reaction of atmospheric air absorbed and expelled at high speed to produce the propulsion force necessary for movement; a system, engine, or aircraft based on burning a fuel in atmospheric oxygen. This type of structural propulsion is specific to modern turbojet airplanes, differing from rockets in that it does not carry its own oxidizer.
• 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.
• Aeration tank — A large basin, reservoir, or industrial technical installation used in wastewater treatment plants for their aerobic biological treatment. Its structural operation relies on the continuous and forced insufflation of air (oxygenation) into the liquid mass, a process that stimulates the growth of microorganisms in the active sludge which decompose polluting organic substances.
• Aphakia — An ocular medical condition characterized by the absence of the crystalline lens from the structure of the eyeball, most commonly occurring following surgical removal due to cataracts or, more rarely, resulting from severe trauma or congenital anomalies. This structural defect induces a severe reduction in focusing ability (a major refractive error) and the complete loss of visual accommodation, requiring correction via an intraocular lens implant, specialized contact lenses, or high-diopter eyeglasses.
• After-school — An educational, recreational, and supervisory program intended for students, conducted immediately after the conclusion of mandatory school classes. As a noun, it designates the institution or specialized center where children do their homework, have lunch, and participate in complementary activities under pedagogical guidance, offering logistical support to working families.
• 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.
• Agentive — Expressing or indicating the agent of an action; a semantic or morphosyntactic category specific to propositional elements that designate the conscious and voluntary author of the state expressed by the verb. It applies to nouns, complements, or suffixes that define the entity performing the deed.
• Agitator — A person who instigates disorder, rebellion, or public unrest, or who carries out intense political propaganda; in a technical sense, it represents a mechanical element (blade, shaft, propeller) or an apparatus used to mix fluids, solutions, or industrial batches. As an adjective, it denotes a factor causing physical agitation or spiritual disturbance.
• Agonist — A chemical substance, drug, or hormone that binds to a specific cellular receptor and triggers a biological response, mimicking the action of an endogenous compound; in muscle physiology, it designates a muscle whose contraction directly produces a specific movement.
• Agung — An active stratovolcano located on the island of Bali, Indonesia, representing the highest geographical point of the island, with an elevation exceeding three thousand meters. In local Indonesian culture and Balinese Hinduism, this mountain is considered deeply sacred, viewed as the central axis of the universe and the dwelling place of the gods, hosting the famous Pura Besakih temple complex on its slopes.
• Aldrofan — A historical or regional commercial name for a pharmaceutical compound utilized in treating acute respiratory disorders or as an adjuvant agent in dermatological therapy; in a generic sense, it represents a specific chemical formulation stored as tablets or stabilized solution according to industrial pharmacological standards.
• Restless runner — Having a tendency, habit, or liking for running continuously, wandering around, or moving swiftly from one place to another; swift-footed, dynamic, restless. In popular usage, the term is often used as a nickname for highly active children or for farm animals that frequently escape their enclosure.
• Allanite — A mineral belonging to the epidote group, black, brown, or gray in color, with a resinous or submetallic luster, containing significant percentages of rare-earth elements (cerium, lanthanum, neodymium, yttrium), alongside traces of thorium or uranium, which give it a weakly radioactive nature. It crystallizes in the monoclinic system and occurs as an accessory mineral in igneous (granites, pegmatites) and metamorphic rocks.
• Allotriosmia — A qualitative olfactory perception disorder characterized by the perversion, distortion, or erroneous and aberrant interpretation of odors; a condition where the patient perceives completely different, strange, or unpleasant smells (for instance, burnt, putrid, or chemical odors) in the presence of normal or familiar olfactory stimuli. This structural neurological phenomenon is clinically associated with parosmia or cacosmia, caused by dysfunctions of the nasal mucosa, olfactory nerve, or temporal lobe.
• Alveoloclasia — A destructive pathological process characterized by the active resorption, dissolution, or fracturing of the bony tissue of the alveolar process under the direct action of osteoclast cells. This severe osteolytic phenomenon, structurally correlated with advanced stages of chronic marginal periodontal diseases, causes the loss of the tooth's rigid support, leading to progressive tooth mobility and the subsequent loss of the affected teeth.
• Americium — A synthetic, highly radioactive chemical element of the actinide series, with atomic number 95 and symbol Am. This silver-colored structural transuranium metal, originally obtained by bombarding plutonium with neutrons, is utilized in precision industrial applications, such as household smoke detectors and alpha radiation sources for laboratory analyses.
• Americium — A variant graphical form or unadapted direct borrowing from English or Latin for the radioactive transuranium chemical element with atomic number 95, named in standard Romanian 'americiu'. It sometimes appears in imported technical papers, international databases, or commercial chemical catalogs to indicate the atomic structure Am of the actinide series.
• Ametropic — A rare prefixed or adjectival form correlated with the lack of normal optical proportion within the eye; a technical term used as an etymological base or restricted variant to describe a structural state of faulty ocular refraction. In old medical textbooks, it serves as a linking element to define refractive errors, indicating a visual apparatus that cannot focus the image on the retina without lenticular correction.