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town (1990 pop. 40,023), McLean co., central Ill.; inc. 1865. It is the center of a productive farming region. Motor vehicles are manufactured in Normal. The town originally grew around Illinois State Univ. (1857; formerly called Illinois State Normal Univ.), which remains a major contributor to its economy.



(to a curve or surface). The normal at a given point of a curve or surface is a line that passes through this point and is perpendicular to the tangent line or tangent plane at the same point of the curve or surface. A plane curve has at each point a single normal that lies in the plane of the curve. If x = f(t) and y = g(t) are parametric equations of a plane curve L, then the equation of the normal at point (x0, y0) of curve L that corresponds to the value to of the parameter; may be written as

For a plane curve defined by the equation F(x,y) = 0, the equation of the normal has the form

A space curve has at each point an infinite set of normals, and these normals all lie in a certain plane (the normal plane). The normal that lies in the osculating plane is called the principal normal. The normal that is perpendicular to the osculating plane is called the binormal. The tangent, the principal normal, and the binormal form the moving trihedral of the curve.

For the surface defined by the equation F(x, y, z) = 0, the normal can be represented by the equations

The concept of the normal plays a significant role not only in differential geometry but also in various applications of this subject, such as geometrical optics and mechanics. The formulation of the fundamental laws of refraction and reflection of light rays is an example from geometrical optics; in mechanics, a mass point or a physical body experiences a reaction directed along the normal when it is displaced along smooth curves or surfaces; in a conservative field, the lines of force at each point are directed along the normal to the isopotential surface that passes through the point.


The average value of a meteorological element over any fixed period of years that is recognized as standard for the country and element concerned.


i. As it pertains to meteorology, the value of an element averaged for a given location over a period of time, normally fifty years, and recognized as a standard.
ii. Equivalent to usual, regular, rational, or standard conditions.
iii. At a right angle to the datum under reference.


1. Psychol
a. being within certain limits of intelligence, educational success or ability, etc.
b. conforming to the conventions of one's group
2. Biology Med (of laboratory animals) maintained in a natural state for purposes of comparison with animals treated with drugs, etc.
3. Chem (of a solution) containing a number of grams equal to the equivalent weight of the solute in each litre of solvent.
4. Chem denoting a straight-chain hydrocarbon: a normal alkane. Prefix: n-, e.g. n-octane
5. Geometry another word for perpendicular
6. Geometry a line or plane perpendicular to another line or plane or to the tangent of a curved line or plane at the point of contact
References in periodicals archive ?
I'll tell you who has made normal no longer of consequence as a word, or likely as a concept.
MAY Nordic Region - Warmer, except southern Sweden/Finland UK - Warmer than normal Northern Mainland - Colder, except Benelux/northern France Southern Mainland - Colder than normal
Collectively, the investigators implanted the devices in 30 percent of the 254 volunteers who had normal T-wave patterns and in 62 percent of the 514 people with T-wave alternans.
9 is considered normal, the risk of breast and uterine cancers (and diabetes) starts to climb above a BMI of 23.
Problem 2: Out-of-sight, out-of-mind By qualifying for the normal purchase and sales exemption, these contractual arrangements are not recorded as assets or liabilities.
Those numbers are even more notable given that the audience for the series premiere of The $treet, a racy heterofest about the sex lives of investment bankers that immediately follows Normal, plummeted by some 5 million viewers.
Strategy: Have the linemen assume normal alignment and cover very quickly to prevent the ball from going into the end zone.
Some of the interest retained by the seller may represent a fee for normal loan servicing and some may represent an excess servicing receivable, such as the right to receive cash flows that exceed normal servicing fees, which is equivalent to an interest-only strip on the portion of the loan sold.
They make the point that, although any single portion of the brain may have fewer than the normal number of cells for that area, the cells in the area are nonetheless morphologically normal.
Southeast - Cooler than normal, especially FL/AL/MS
The researchers compared how normal mice and mice lacking the gene to make ghrelin reacted when an old toy in their cages was swapped for a new one.
Generation and analysis of late-onset disease models or long-lived mutants that can be used to identify, clone, and characterize genes involved in normal and pathological aging.