All articles starting with P

Passive design

Passive design is an architectural and building-engineering approach that heats and cools buildings through orientation, insulation, shading, thermal mass, and ventilation rather than mechanical systems.

Passive DNS

Passive DNS (pDNS) is a technique for collecting DNS response data at network sensors and archiving it to answer historical questions, described by Florian Weimer in 2005.

Passive dynamic walking

Passive dynamic walking is a mode of bipedal locomotion in which an unpowered, uncontrolled robot walks stably down a shallow slope, named by Tad McGeer in 1990.

Oct 21, 2026

Passive Euthanasia

Passive euthanasia, also called allowing to die or negative euthanasia, is mercy-motivated withholding or withdrawal of life-prolonging treatment, distinguished from active euthanasia and physician-assisted dying by act versus omission.

Passive house

A passive house (Passivhaus) is an ultra-low-energy building standard limiting heating demand to 15 kWh per square meter yearly, first demonstrated in Darmstadt, Germany, in 1991.

Passive House Planning Package

The Passive House Planning Package (PHPP) is an Excel-based energy balancing and design tool for energy-efficient buildings, first released by the Passive House Institute in Darmstadt, Germany, in 1997.

Passive immunity

Passive immunity: protection by transferred antibodies, natural (placenta, breast milk) or artificial (immune globulin, monoclonal antibodies). Immediate but short-lived, weeks to months; began with 1890s diphtheria antitoxin.

Passive immunotherapy

Passive immunotherapy is the administration of pre-made antibodies or immune cells to a patient to prevent or treat disease, used after exposure or for toxins, with protection that is temporary.

Passive income

Passive income is money earned with little ongoing work, such as dividends, rent, or royalties; in US tax law it means income from activities the taxpayer does not materially participate in.

Passive infrared sensor

A passive infrared sensor, also known as a PIR sensor or passive infrared detector, detects moving people or warm objects by measuring changes in the infrared radiation they emit.

Oct 10, 2026

Passive management

Passive management is a fund-management approach that builds a portfolio to replicate the return of a market index, such as the S&P 500, rather than beat it.

Passive margin

Passive margin is a tectonic transition between continental and oceanic crust, forming where a continent rifted apart, such as along the Atlantic coast of North America.

Passive optical network

A passive optical network (PON) is a fiber-optic access network using unpowered splitters to link one provider terminal to many customers, the dominant fiber-to-the-home system.

Passive radar

Passive radar is a class of radar that detects and tracks targets without transmitting any signal of its own, instead exploiting existing broadcast, communications, or radionavigation signals.

Oct 22, 2026

Passive radiative cooling

Passive radiative cooling (PRC) is a zero-energy cooling method in which surfaces reflect most sunlight and emit infrared heat through the atmospheric transparency window to space, reducing air-conditioning demand.

Passive rewilding

Passive rewilding: spontaneous ecosystem recovery via natural succession on abandoned land, without intervention or species reintroduction; contrasted with trophic, Pleistocene, and ecological rewilding; evidence from Monks Wood, Alladale, and meta-analyses.

Passive sampling

Passive sampling is an analytical chemistry technique where chemicals in air or water move onto a sorbent without pumps or power, giving time-weighted average concentrations.

Passive scattering proton therapy

Passive scattering proton therapy (PSPT) is a proton radiotherapy delivery method that widens a narrow proton beam with scattering material to cover the whole tumor uniformly.

Passive seismology

Passive seismology is the imaging of Earth's subsurface using natural seismic sources, earthquakes and ambient noise, instead of controlled artificial sources, at much lower cost.

Passive sensing

Passive sensing is the collection of behavioral, physiological, or environmental data through embedded device sensors such as accelerometers and GPS, continuously and without requiring active user participation.

Passive smoking

Passive smoking, or secondhand smoke exposure, is inhaling tobacco smoke as a nonsmoker; about 85% sidestream smoke, no safe level, causes lung cancer, heart disease, stroke, and child respiratory illness, killing about 1.3 million people yearly.

Passive sonar

Passive sonar is a method of underwater detection that listens for sound radiated by targets such as submarines, ships, and whales, without transmitting any sound of its own, using hydrophones.

Passive stretching

Passive stretching is a flexibility technique in which a therapist, gravity, or a device lengthens muscles and moves joints without active effort, used in rehabilitation and sports medicine.

Passive transport

Passive transport: movement of substances across cell membranes down concentration gradients without cell energy, including simple diffusion, facilitated diffusion via channels and carriers, osmosis, and filtration.

Passive voice

Passive voice: a construction in which the patient is the clause subject and the agent is omitted or demoted to a by phrase. Built with be plus a past participle; English lost the Old English weorðan auxiliary and later added get- and progressive passives.