18-letter words containing p, o, r
- radical expression — an expression in which radical signs appear.
- raman spectroscopy — a form of spectroscopy which uses the Raman effect for studying molecules
- rapid eye movement — rapidly shifting, continuous movements of the eyes beneath closed lids during the stage of sleep characterized by dreaming.
- rational operation — any of the mathematical operations of addition, subtraction, multiplication, and division.
- reactive component — the component in an alternating-current circuit that does not contribute power because it is 90° out of phase with the voltage or current.
- real-time computer — a computer that can process data or information almost immediately
- recess appointment — a person appointed to an office by the President of the United States without approval from the Senate because the Senate is in recess
- reciprocating pump — A reciprocating pump is a pump which uses a backward and forward movement to move a fluid.
- recovery operation — the process of locating and retrieving bodies, esp following an explosion or natural disaster
- red-spotted purple — any color having components of both red and blue, such as lavender, especially one deep in tone.
- redevelopment area — an urban area in which all or most of the buildings are demolished and rebuilt
- reentering polygon — a polygon having one or more reentering angles.
- registered company — a company which has officially registered its business
- registration plate — a plate mounted on the front and back of a motor vehicle bearing the registration number
- regular expression — 1. (text, operating system) (regexp, RE) One of the wild card patterns used by Perl and other languages, following Unix utilities such as grep, sed, and awk and editors such as vi and Emacs. Regular expressions use conventions similar to but more elaborate than those described under glob. A regular expression is a sequence of characters with the following meanings (in Perl, other flavours vary): An ordinary character (not one of the special characters discussed below) matches that character. A backslash (\) followed by any special character matches the special character itself. The special characters are: "." matches any character except newline; "RE*" (where RE is any regular expression and the "*" is called the "Kleene star") matches zero or more occurrences of RE. If there is any choice, the longest leftmost matching string is chosen. "^" at the beginning of an RE matches the start of a line and "$" at the end of an RE matches the end of a line. (RE) matches whatever RE matches and \N, where N is a digit, matches whatever was matched by the RE between the Nth "(" and its corresponding ")" earlier in the same RE. Many flavours use \(RE\) instead of just (RE). The concatenation of REs is a RE that matches the concatenation of the strings matched by each RE. RE1 | RE2 matches whatever RE1 or RE2 matches. \< matches the beginning of a word and \> matches the end of a word. Many flavours use "\b" instead as the special character for "word boundary". RE{M} matches M occurences of RE. RE{M,} matches M or more occurences of RE. RE{M,N} matches between M and N occurences. Other flavours use RE\{M\} etc. Perl provides several "quote-like" operators for writing REs, including the common // form and less common ??. A comprehensive survey of regexp flavours is found in Friedl 1997 (see below). 2. Any description of a pattern composed from combinations of symbols and the three operators: Concatenation - pattern A concatenated with B matches a match for A followed by a match for B. Or - pattern A-or-B matches either a match for A or a match for B. Closure - zero or more matches for a pattern. The earliest form of regular expressions (and the term itself) were invented by mathematician Stephen Cole Kleene in the mid-1950s, as a notation to easily manipulate "regular sets", formal descriptions of the behaviour of finite state machines, in regular algebra.
- reinforced plastic — plastic with fibrous matter, such as carbon fibre, embedded in it to confer additional strength
- repayment mortgage — a mortgage that you pay back in monthly repayments which consist of the accrued interest in addition to the original amount borrowed
- repeat performance — sth done again
- report an accident — If you report an accident, you inform an insurer or the police or other authorities that an accident has occurred.
- reporters' gallery — an area in parliament reserved for journalists and reporters
- repossession order — If a bank or building society issues a repossession order, they officially tell someone that they are going to repossess their home.
- reprocessing plant — a plant where materials are treated in order to make them reusable
- reproduction proof — repro proof.
- respiratory arrest — cessation of breathing
- respiratory system — the system by which oxygen is taken into the body and an exchange of oxygen and carbon dioxide takes place; in mammals the system includes the nasal passages, pharynx, trachea, bronchi, and lungs.
- resurrection plant — a desert plant, Selaginella lepidophylla, occurring from Texas to South America, having stems that curl inward when dry.
- retirement pension — income: no longer at work
- reverse psychology — (in nontechnical use) a method of getting another person to do what one wants by pretending not to want it or to want something else or something more.
- rhodes scholarship — one of a number of scholarships at Oxford University, established by the will of Cecil Rhodes, for selected students (Rhodes scholars) from the British Commonwealth and the United States.
- ribbon development — housing or commercial buildings built along a stretch of road.
- room occupancy tax — Room occupancy tax is a tax that guests at a hotel have to pay in order to stay there.
- root canal therapy — endodontics.
- rooted to the spot — If you are rooted to the spot, you are unable to move because you are very frightened or shocked.
- russo-japanese war — the war (1904–1905) between Russia and Japan.
- salt of phosphorus — a colorless, odorless, crystalline, water-soluble solid, NaNH 4 HPO 4 ⋅4H 2 O, originally obtained from human urine: used as a blowpipe flux in testing metallic oxides.
- scholarship holder — a person who, because of academic merit, receives financial aid for their studies
- scissors-and-paste — designating or of a piece of writing that has been assembled from a variety of sources rather than by original research, often in a hasty or uninspired way
- seafloor spreading — a process in which new ocean floor is created as molten material from the earth's mantle rises in margins between plates or ridges and spreads out.
- seasonal promotion — Seasonal promotions are items marketed to customers at the appropriate time of year, such as coats in the winter and bathing suits in the summer.
- secondary syphilis — the second stage of syphilis, characterized by eruptions of the skin and mucous membrane.
- self-comprehending — to understand the nature or meaning of; grasp with the mind; perceive: He did not comprehend the significance of the ambassador's remark.
- self-preoccupation — the state of being preoccupied.
- semiprecious stone — See at semiprecious.
- separation anxiety — the normal fear and apprehension expressed by infants when removed from their mothers or approached by strangers.
- september holidays — a period of time in September when people do not have to go to school, college or work
- septic sore throat — an acute, toxic, streptococcus infection of the throat producing fever, tonsillitis, and other serious effects.
- set priority level — (SPL) The way traditional Unix kernels implement mutual exclusion by running code at high interrupt priority levels and thus blocking lower level interrupts.
- shatterproof glass — glass designed to resist shattering
- sheltered workshop — a place of employment for persons with disabilities where their rights are protected and their needs are met.
- shipping container — a large, strong container, usually of metal, used to store goods in during shipment