pennill
A kind of Welsh verse in which the singer has to change words and measure according to the variations of an accompanist on the harp.

pennillion
plural of pennill

pennills
plural of pennill

penniworth
Obsolete form of pennyworth.

penniworths
plural of penniworth

pennorth
Alternative form of pennyworth.

pennorths
plural of pennorth

pennyland
An old Scots unit of measure of land.

pennylands
plural of pennyland

pennyweight
A unit of mass equal to 24 grains, or ¹⁄₂₀ of a troy ounce.

pennyweights
plural of pennyweight

pennyworth
The amount that can be bought for a penny.
A small quantity or value.
A good bargain.

pennyworths
plural of pennyworth

pentapodies
plural of pentapody

pentapody
A measure, verse, or series consisting of five feet.

pentastichs
plural of pentastich

pentet
Synonym of quintet.
In NMR spectroscopy, a group of five peaks whose intensity is in the ratio 1:4:6:4:1. Note, that "pentet" is a non-standard notation; it should be replaced by "quintet" (compare "quartet" and "triplet" are also based on Latin numbering).

pentets
plural of pentet

peppercorn
The seeds of the pepper plant Piper nigrum, commonly used as a spice, usually ground or crushed.
A small, insignificant quantity; a whit or jot.
A small, insignificant quantity; a whit or jot.

peppercorns
plural of peppercorn

peptid
Archaic form of peptide.

peptide
Any of a class of organic compounds consisting of various numbers of amino acids in which the amine of one is reacted with the carboxylic acid of the next to form an amide bond.
The peptide bond itself.
performance-enhancing drugs, often a synthetic peptide compound

peptides
plural of peptide

peptids
plural of peptid

peracid
Any acid that contains a peroxy group - e.g. peracetic acid
The oxyacid of a particular element that has the largest number of oxygen atoms - e.g. perchloric acid

peracids
plural of peracid

percentage
The amount, number or rate of something, regarded as part of a total of 100; a part of a whole.
A share of the sales, profits, gross margin or similar.
Benefit or advantage.

percentages
plural of percentage

percenter
A member of a group that forms a specified percentage of a population.
An agent.

percenters
plural of percenter

performabilities
plural of performability

performability
A measurement of how well a system performs over a period of time, regardless of the presence of faults.

pergunnah
Dated form of pargana.

pergunnahs
plural of pergunnah

periactus
Alternative form of periaktos.

periaktos
A revolving structure used to change scenes rapidly in a theatre: a tall prism-shaped frame or screen at the side entrances, each carrying a number of scenes changed by turning the frames.

periapse
A periapsis.

periapses
plural of periapse
plural of periapsis
Synonym of periapsides.
Misspelling of periapsis.

periapsides
plural of periapsis

periapsis
The point of a body's (elliptical) orbit in a 2-body gravitational system such that the distance between the two bodies (measured from their respective centres of mass) is at its minimum.
The minimum distance between the two bodies in such a system.

periapsises
plural of periapsis

pericine
One of a number of indole alkaloids found in the tree Picralima nitida.

periot
A unit of weight, 9,600 of which make a grain.

periots
plural of periot

perissodactyl
Any ungulate mammal with an odd number of toes and belonging to the Perissodactyla, an equid, a tapir, or a rhinoceros.

perissodactyls
plural of perissodactyl

permeabilities
plural of permeability

permeability
The property of being permeable.
The rate of flow of a fluid through a porous material.
A measure of the ability of a rock to transmit fluids (such as oil or water).
A quantitative measure of the degree of magnetization of a material in the presence of an applied magnetic field (measured in newtons per ampere squared in SI units).

permeance
A measure of the degree to which a material allows a fluid to permeate it.
The reciprocal of reluctance in a magnetic circuit; the analogue of conductance in an electrical circuit.

permeances
plural of permeance

permillage
The amount, number or rate of something, regarded as part of a total of 1000.

permillages
plural of permillage

permuton
A probability measure Φ on the σ-algebra of Borel sets of the unit square [0,1]² such that Φ has uniform marginals (that is, Φ ([α, β] × [0,1]) = Φ ([0,1] × [α, β]) = β − α for every 0 ≤ α ≤ β ≤ 1).

permutons
plural of permuton

peroxyacid
Synonym of peracid (“acid containing an acidic -OOH group”).

peroxyacids
plural of peroxyacid

perplexities
plural of perplexity

perplexity
The state or quality of being perplexed.
Something that perplexes.
A measure of how well a probability distribution or model predicts a sample.

persistance
Misspelling of persistence.

persistence
The property of being persistent.
Of data, the property of continuing to exist after the termination of the program.
Continuation of the previous day's weather (particularly temperature and precipitation statistics).
The number of times an operation can be iteratively applied to a number before it reaches a permanently constant state.

persistences
plural of persistence

persistencies
plural of persistency

persistency
The state or characteristic of being persistent.
A measure of how much something persists.

perspectives
plural of perspective

pesharim
plural of pesher

petabecquerel
An SI unit of radioactivity equal to 10¹⁵ becquerels. Symbol: P

petabecquerels
plural of petabecquerel

petaflop
Either of two units of measure of the calculating speed of a computer:
Either of two units of measure of the calculating speed of a computer:

petaflops
plural of petaflop

petagram
An SI unit of mass equal to 10¹⁵ grams. Symbol: Pg
An SI unit of mass equal to 10¹⁵ grams. Symbol: Pg
Sometimes used in Carbon Dioxide numbers, it is equivalent to Metric Gigatons (Giga) 10⁹ x (Ton) 10³ x (kg) 10³ = 10¹⁵

petagramme
Alternative spelling of petagram.

petagrammes
plural of petagramme

petagrams
plural of petagram

petahertz
An SI unit of frequency equal to 10¹⁵ hertz.

petajoule
An SI unit of energy equal to 10¹⁵ joules. Symbol: PJ

petajoules
plural of petajoule

petakelvin
An SI unit of temperature equal to 10¹⁵ kelvins. Symbol: PK

petaliter
A unit of volume equivalent to 10¹⁵ liters. Symbol: Pl

petaliters
plural of petaliter

petalitre
A unit of volume equivalent to 10¹⁵ litres. Symbol: Pl

petalitres
plural of petalitre

petametre
An SI unit of length equal to 10¹⁵ metres. Symbol: Pm

petametres
plural of petametre

petasecond
An SI unit of time equal to 10¹⁵ seconds. Symbol: Ps. (= 31 709 800 years)

petaseconds
plural of petasecond

petaton
A measure of the strength of an explosion or a bomb based on how many quadrillion tons of TNT would be needed to produce the same energy.

petatons
plural of petaton

petawatt
An SI unit of power equal to 10¹⁵ watts. Symbol: PW. An amount of power much larger than all the power generated by all power stations on Earth. (Consuming 1 petawatt during a duration of 1 hour would consume 1 petawatt-hour of energy.)

petawatts
plural of petawatt

petide
Misspelling of peptide.

petong
Obsolete form of paktong.

pewful
An amount sufficient to fill a pew.

pewfuls
plural of pewful

pewsful
plural of pewful

phaiophyll
Any of a number of brown pigments found in plant leaves.

phantoplexes
plural of phantoplex

pharmacometabolomics
The direct measurement of metabolites in an individual's bodily fluids, in order to predict or evaluate the metabolism of pharmaceutical compounds.

phasor
A representation of a complex number in terms of a complex exponential.
A plotted line whose length and angle represent the amplitude and phase, respectively, of a sinusoidally varying quantity such as an alternating current.

phasors
plural of phasor

phenetics
A form of numerical systematics in which organisms are grouped based upon the total or relative number of shared characteristics.