21-letter words containing p, r, e, i, l, y
- primitive dicotyledon — any living relative of early angiosperms that branched off before the evolution of monocotyledons and eudicotyledons. The group comprises about 5 per cent of the world's plants
- privacy enhanced mail —
- psychological warfare — the use of propaganda, threats, and other psychological techniques to mislead, intimidate, demoralize, or otherwise influence the thinking or behavior of an opponent.
- psychoneuroimmunology — the study of the effects of psychological factors on the immune system
- public address system — loudspeaker
- public-address system — a combination of electronic devices that makes sound audible via loudspeakers to many people, as in an auditorium or out of doors.
- public-key encryption — (cryptography) (PKE, Or "public-key cryptography") An encryption scheme, introduced by Diffie and Hellman in 1976, where each person gets a pair of keys, called the public key and the private key. Each person's public key is published while the private key is kept secret. Messages are encrypted using the intended recipient's public key and can only be decrypted using his private key. This is often used in conjunction with a digital signature. The need for sender and receiver to share secret information (keys) via some secure channel is eliminated: all communications involve only public keys, and no private key is ever transmitted or shared. Public-key encryption can be used for authentication, confidentiality, integrity and non-repudiation. See also knapsack problem.
- pulse height analyser — a multichannel analyser that sorts pulses into selected amplitude ranges
- pulse height analyzer — an instrument that records or counts an electrical pulse if its amplitude falls within specified limits: used in nuclear physics research for the determination of energy spectra of nuclear radiations
- quality point average — grade point average.
- real operating system — (operating system, abuse) The sort the speaker is used to. People from the BSDophilic academic community are likely to issue comments like "System V? Why don't you use a *real* operating system?", people from the commercial/industrial Unix sector are known to complain "BSD? Why don't you use a *real* operating system?", and people from IBM object "Unix? Why don't you use a *real* operating system?" See holy wars, religious issues, proprietary, Get a real computer!.
- relative permeability — the ratio of the permeability of a medium to that of free space
- relative permittivity — Electricity. the ratio of the flux density produced by an electric field in a given dielectric to the flux density produced by that field in a vacuum.
- residual unemployment — the unemployment that remains in periods of full employment, as a result of those mentally, physically, or emotionally unfit to work
- reverse polish syntax — postfix notation
- schlieren photography — a type of photography which records schlieren
- scorched earth policy — a military practice of devastating the property and agriculture of an area before abandoning it to an advancing enemy.
- scorched-earth policy — a military practice of devastating the property and agriculture of an area before abandoning it to an advancing enemy.
- social inquiry report — (in Britain) a report on a person and his or her circumstances, which may be required by a court before sentencing and is made by a probation officer or a social worker from a local authority social services department
- split-screen facility — a facility allowing different scenes to be shown on screen at the same time
- sport utility vehicle — a rugged vehicle with a trucklike chassis and four-wheel drive, designed for occasional off-road use. Abbreviation: SUV.
- sport-utility vehicle — a rugged vehicle with a trucklike chassis and four-wheel drive, designed for occasional off-road use. Abbreviation: SUV.
- supplementary benefit — (formerly) an extra amount of money that is paid to someone by the government, in addition to their normal income. Replaced by income support in 1988
- theoretical physicist — a scientist who studies theoretical physics
- threshold wage policy — a policy whereby wages are increased in accordance with inflation
- to be public property — to be publicly owned
- ulster unionist party — a Northern Irish political party advocating the maintenance of union with the UK
- uncertainty principle — the principle of quantum mechanics, formulated by Heisenberg, that the accurate measurement of one of two related, observable quantities, as position and momentum or energy and time, produces uncertainties in the measurement of the other, such that the product of the uncertainties of both quantities is equal to or greater than h/ 2 π, where h equals Planck's constant.
- west university place — a city in SE Texas.
- yellow lady's-slipper — a showy orchid, Cypripedium calceolus, of eastern North America, having purple-tinged yellow flowers with an inflated lip petal.