18-letter words containing o, s, n, a
- parathyroid glands — any of several small oval glands usually lying near or embedded in the thyroid gland.
- pass the hat round — to collect money, as for a cause
- passing modulation — a modulation of a temporary nature.
- passing-out parade — a ceremonial parade of cadets who have completed their training
- pathname separator — (file system) The character used to separate elements of a path or pathname. Under Unix and POSIX.1 compliant systems the pathname separator is the (forward) slash, in MS-DOS backslash serves the same purpose. For obvious reasons the no directory or file name can contain this character.
- patron of the arts — someone who acts as a patron to or supports charities, organizations, and individuals that work in or concern the arts
- pay one's respects — a particular, detail, or point (usually preceded by in): to differ in some respect.
- peano's postulates — a collection of axioms concerning the properties of the set of all positive integers, including the principle of mathematical induction.
- peasant proprietor — a peasant who owns land, especially the land he or she tills.
- pectoral sandpiper — an American sandpiper, Calidris melanotos, the male of which, when courting, inflates its chest conspicuously.
- pellitory of spain — a small Mediterranean plant, Anacyclus pyrethrum, the root of which contains an oil formerly used to relieve toothache: family Asteraceae (composites)
- percussion flaking — a method of forming a flint tool by striking flakes from a stone core with another stone or a piece of bone or wood.
- performance artist — an artist that is involved in a theatrical presentation that incorporates various art forms, such as dance, sculpture, music, etc
- pernicious anaemia — Pernicious anaemia is a very severe blood disease.
- personal allowance — the amount of money you are allowed to earn each year without paying tax
- personal assistant — aide
- personal bodyguard — a person employed to protect a particular person
- personal exemption — Your personal exemption is the amount of money that is deducted from your gross income before you have to start paying income tax.
- personal insurance — insurance on personal risk, such as car insurance, health insurance or loss of earnings insurance
- personal organizer — a small notebook with sections for personal information, as dates and addresses.
- pescadores-islands — (used with a plural verb) Penghu.
- phanerocrystalline — (of a rock) having the principal constituents in the form of crystals visible to the naked eye.
- phantasmagorically — having a fantastic or deceptive appearance, as something in a dream or created by the imagination.
- phosphatidylserine — any of a class of phospholipids occurring in biological membranes and fats
- photoisomerization — isomerization induced by light.
- photosensitization — to make (a material) photosensitive, as by the application of a photosensitive emulsion.
- physical education — systematic instruction in sports, exercises, and hygiene given as part of a school or college program.
- physical inventory — To carry out a physical inventory is to count all the stock on hand.
- pitch-and-run shot — chip shot.
- plains grasshopper — a large, destructive short-horned grasshopper, Brachystola magna, of the western U.S., marked by pinkish hind wings.
- plate-glass window — a window that has glass which has been formed by rolling
- play cat and mouse — Also called cat and rat. a children's game in which players in a circle keep a player from moving into or out of the circle and permit a second player to move into or out of the circle to escape the pursuing first player.
- play second fiddle — be considered less important
- play someone false — to deceive, cheat, hoodwink, or betray someone
- policeman's helmet — a Himalayan balsaminaceous plant, Impatiens glandulifera, with large purplish-pink flowers, introduced into Britain
- political prisoner — sb imprisoned for political dissidence
- political question — a question regarded by the courts as being a matter to be determined by another department of government rather than of law and therefore one with which they will not deal, as the recognition of a foreign state.
- polynesian tattler — a sandpiper, H. incanus, native to the Pacific coastal regions
- population density — ratio: inhabitants to area
- population figures — population totals; statistics relating to the size of populations
- portuguese guinean — of or relating to Portuguese Guinea, a former name for Guinea-Bissau, or its inhabitants
- post-revolutionary — of, pertaining to, characterized by, or of the nature of a revolution, or a sudden, complete, or marked change: a revolutionary junta.
- postmaster general — the executive head of the postal system of a country.
- postmillenarianism — postmillennialism.
- postviral syndrome — debilitating condition occurring as a sequel to viral illness
- potassium myronate — sinigrin.
- pragmatic sanction — any one of various imperial decrees with the effect of fundamental law.
- prayer of manasses — a book of the Apocrypha.
- precedence lossage — /pre's*-dens los'*j/ A misunderstanding of operator precedence resulting in unintended grouping of arithmetic or logical operators when coding an expression. Used especially of mistakes in C code due to the nonintuitively low precedence of "&", "|", "^", "<<" and ">>". For example, the following C expression, intended to test the least significant bit of x, x & 1 == 0 is parsed as x & (1 == 0) which is always zero (false). Some lazy programmers ignore precedence and parenthesise everything. Lisp fans enjoy pointing out that this can't happen in *their* favourite language, which eschews precedence entirely, requiring one to use explicit parentheses everywhere.
- predation pressure — the effect of predation upon a population, resulting in the decrease in size of that population.