# normal

Pronunciation: US say "NOR-muhl" /ˈnɔɹ.ml̩/; UK say "NAW-muhl" /ˈnɔː.ml̩/

## Adjective

1. Following accepted norms or rules, or fitting a regular and expected pattern.
   - Simple: Following the usual rules or pattern, the way most things happen.
   - _The factory resumed normal operations once the power was restored._
   - _It is perfectly normal for prices to rise a little each year._
3. Healthy and behaving as usual, rather than sick or unlike oneself.
   - Simple: Healthy and feeling like your usual self, not sick.
   - _After two days of antibiotics, the dog was eating again and acting completely normal._
   - _He didn't seem normal this morning, so we kept him home from school._
4. Having a normal distribution, or relating to a random variable whose values follow that bell-shaped distribution.
   - Simple: Following the common bell-shaped pattern that many measurements make when you graph them.
   - _Many natural measurements, such as height, are approximately normal._
   - _When the residuals are normal, standard confidence intervals apply directly._
6. Perpendicular to the tangent of a curve, or to the tangent plane of a surface, at the point of contact.
   - Simple: Pointing straight out at a right angle from a curve or surface.
   - _The force acts in a direction normal to the inclined plane._
   - _At each point of the sphere, the radius is normal to the surface._
8. Concerned with training teachers and instructing them in the established methods of education.
   - Simple: Used to describe a school that trains people to become teachers.
   - _Many future educators trained at a normal school in the nineteenth century._
   - _Before it became a large university, the campus was a small normal school for future teachers._
10. Passionately and obsessively interested in a particular subject. *(slang)*
   - Simple: Very strongly interested in something, almost unable to think about anything else.
   - _She has been completely normal about her new puppy, posting forty photos of him since Tuesday._
   - _The fans were so normal about the series that they memorized every line._

## Noun

2. The condition or state of affairs that counts as usual or expected.
   - Simple: The way things usually are when nothing unusual is happening.
   - _Working from home has become the new normal for many families._
   - _It took weeks for life to settle back into normal._
5. An ordinary person who fits into mainstream society, rather than one living an alternative lifestyle. *(slang)*
   - Simple: An ordinary person who fits in with mainstream society instead of living an alternative lifestyle.
   - _To the festival regulars, anyone in a suit was just a normal._
   - _She grew tired of being treated like a normal by her artist friends._
7. A line or vector at a right angle to a given line, plane, or surface, pointing straight out from it.
   - Simple: A line that points straight out at a right angle from a surface or another line.
   - _To reflect the ray, we first find the normal at the point of impact._
   - _Each face of the model stores a normal that defines which way it points._
9. A healthy person, especially one used as a baseline for comparison against someone who is ill.
   - Simple: A healthy person, used in medical studies as a comparison to someone who is sick.
   - _Researchers compared brain scans from patients with scans from a group of healthy normals._
   - _Each normal in the control group underwent the same screening._

## Other meanings

- (adjective) Of a signal or set of points: in the designated default position it rests in when not operated, as opposed to reverse.
- (adjective) Describing a hydrocarbon, or a related compound, whose carbon atoms form a single straight, unbranched chain, as in n-butane.
- (adjective) Describing a solution that contains one equivalent weight of dissolved substance per liter of solution.
- (adjective) Describing a mode of vibration in which all parts of an object oscillate at the same frequency.
- (adjective) Of a subgroup: whose cosets form a group under the operation inherited from the larger group.
- (adjective) (mathematics) Of a matrix or operator: commuting with its conjugate transpose or adjoint.
- (adjective) Of a topological space: in which any two disjoint closed sets can be enclosed in disjoint open neighborhoods.
- (adjective) Of a number: having digits that, in a given base, distribute every possible block of length n with equal frequency.
- (adjective) Of a field extension: that arises as the splitting field of a family of polynomials over the base field K.
- (adjective) (mathematics) Of an integral domain, ring, or scheme: integrally closed, or locally integrally closed at every prime or point.
- (adjective) Of a family of complex functions: having compact closure, so that every sequence drawn from it contains a subsequence converging uniformly on each compact subset.
- (adjective) Of a function on the ordinals: strictly increasing and continuous with respect to the order topology.
- (adjective) Of a morphism, being the kernel or cokernel of some morphism; of a category, having only such monomorphisms and epimorphisms.

## Origin

Latin norma meant "carpenter's square" and is of uncertain origin. From it came normalis, "made according to a carpenter's square," which later also meant "according to a rule." One early English meaning was "perpendicular, forming a right angle," but the modern senses come from the Late Latin meaning "according to a rule." During the 1800s, as people measured things like height and weight, the most common values were called normal, and the word then extended to values seen as healthy or desirable.

Source: DictionaryAI, https://dictionaryai.com/define/normal (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).