normal

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Conforming with, adhering to, or constituting a norm, standard, pattern, level, or type; typical: normal room temperature; one's normal weight; normal diplomatic relations.
2. adj. Biology Functioning or occurring in a natural way; lacking observable abnormalities or deficiencies.
3. adj. Chemistry Designating a solution having one gram equivalent weight of solute per liter of solution.
4. adj. Chemistry Designating an aliphatic hydrocarbon having a straight and unbranched chain of carbon atoms.
5. adj. Mathematics Being at right angles; perpendicular.
6. adj. Mathematics Perpendicular to the direction of a tangent line to a curve or a tangent plane to a surface.
7. adj. Relating to or characterized by average intelligence or development.
8. adj. Free from mental illness; sane.
9. n. Something normal; the standard: scored close to the normal.
10. n. The usual or expected state, form, amount, or degree.
11. n. Correspondence to a norm.
12. n. An average.
13. n. Mathematics A perpendicular, especially a perpendicular to a line tangent to a plane curve or to a plane tangent to a space curve.

Century Dictionary and Cyclopedia

1. According to a rule, principle, or norm; conforming to established law, order, habit, or usage; conforming with a certain type or standard; not abnormal; regular; natural.
2. Serving to fix a standard; intended to set the standard: as, a normal school (see below).
3. In music, standard or typical: as, normal pitch or tone, a pitch or tone of absolute acoustical value, which is used as a standard of comparison. See key, 7, and natural key (under key).
4. In geometry, perpendicular: noting the position of a straight line drawn at right angles to the tangent-line of a curve, or to the tangent-plane of a surface, at the point of contact. The section of a surface by a plane containing a normal drawn from any point is called the normal section at that point.
5. Synonyms Regular, Ordinary, Normal. That which is regular conforms to rule or habit, and is opposed to that which is irregular, fitful, or exceptional. That which is ordinary is of the usual sort and excites no surprise; it is opposed to the uncommon or the extraordinary. That which is normal conforms or may be figuratively viewed as conforming to nature or the principles of its own constitution: as, the normal action of the heart; the normal operation of social influences; the normal state of the market.
6. n. In geometry, a perpendicular; the straight line drawn from any point in a curve in its plane at right angles to the tangent at that point; or the straight line drawn from any point in a surface at right angles to the tangent-plane at that point. See cut under binomial.
7. In chem.:
8. Of a salt, having all the readily replaceable or basic hydrogen of the corresponding acid replaced by one or more metals or strongly electropositive radicals: distinguished from an acid salt in which this replacement is only partial.
9. Of a solution for use in volumetric analysis, containing of the dissolved chemical substance the reactive equivalent of 1 gram of hydrogen in 1 liter of the solution at 16° C. See normal solution.
10. n. The rule; the standard.
11. n. In biology, a species or race considered as a fixed standard which individual organisms may approach by heredity and from which they may recede by variation. The conception of a normal is statistical rather than biological, for there is no evidence that an exceptional specimen of a species differs, as such, from an average specimen in any essential or qualitative way. The notion of a species as a fixed standard belongs to the pre-Darwinian period in the history of biology.
12. n. In meteorology, the average of a large number of observed values of any given meteorological element, for example, mean temperature, pressure, or rainfall for any hour of the day, or day of the year. The number of observations must be so large that a second group of the same number would give the same average or normal. The normals for the hours of local mean solar time may be corrected or adjusted so as to become normals for the hours of any other standard of time.
13. n. In compar. psychol., an untrained or uninjured animal whose behavior is made the standard of reference for the interpretation of the conduct of other, trained or operated animals.

Wiktionary

1. adj. According to norms or rules.
2. adj. Usual; ordinary.
3. adj. Healthy; not sick or ill
4. adj. Pertaining to a school to teach teachers how to teach.
5. adj. chemistry of, relating to, or being a solution containing one equivalent weight of solute per litre of solution.
6. adj. organic chemistry Describing a straight chain isomer of an aliphatic hydrocarbon, or an aliphatic compound in which a substituent is in the 1- position of such a hydrocarbon
7. adj. physics (Of a mode in an oscillating system) In which all parts of an object vibrate at the same frequency; See normal mode
8. adj. geometry Perpendicular to a tangent line or derivative of a surface in Euclidean space.
9. adj. algebra (Of a subgroup) whose cosets form a group
10. adj. algebra (Of a field extension of a field K) which is the splitting field of a family of polynomials in K
11. adj. probability theory, statistics (Of a distribution) which has a very specific bell curve shape
12. adj. complex analysis (Of a family of continuous functions) which is pre-compact
13. adj. set theory (Of a function from the ordinals to the ordinals) which is strictly monotonically increasing and continuous with respect to the order topology
14. adj. linear algebra (Of a matrix) which commutes with its conjugate transpose
15. adj. functional analysis (Of a Hilbert space operator) which commutes with its adjoint
16. adj. category theory (Of an epimorphism) which is the cokernel of some morphism
17. adj. category theory (Of a monomorphism) which is the kernel of some morphism
18. adj. category theory (Of a morphism) which is a normal epimorphism or a normal monomorphism
19. adj. category theory (Of a category) in which every monomorphism is normal
20. adj. whose digits, in any base representation, enjoy a uniform distribution
21. adj. topology (Of a topology) in which disjoint closed sets can be separated by disjoint neighborhoods
22. adj. rail transport, of points in the default position, set for the most frequently used route.
23. n. geometry A line or vector that is perpendicular to another line, surface, or plane.
24. n. slang A person who is normal, who fits into mainstream society, as opposed to those who live alternative lifestyles.

GNU Webster's 1913

1. adj. According to an established norm, rule, or principle; conformed to a type, standard, or regular form; performing the proper functions; not abnormal; regular; natural; analogical.
2. adj. (Geom.) According to a square or rule; perpendicular; forming a right angle. Specifically: Of or pertaining to a normal.
3. adj. (Chem.) Standard; original; exact; typical.
4. adj. (Quantitative Analysis) Denoting a solution of such strength that every cubic centimeter contains the same number of milligrams of the element in question as the number of its molecular weight.
5. adj. (Chem.) Denoting certain hypothetical compounds, as acids from which the real acids are obtained by dehydration; thus, normal sulphuric acid and normal nitric acid are respectively S(OH)6, and N(OH)5.
6. adj. (Organ. Chem.) Denoting that series of hydrocarbons in which no carbon atom is bound to more than two other carbon atoms; Cf. Iso-.
7. n. (Geom.) Any perpendicular.
8. n. (Geom.) A straight line or plane drawn from any point of a curve or surface so as to be perpendicular to the curve or surface at that point.

WordNet 3.0

1. adj. forming a right angle
2. adj. conforming with or constituting a norm or standard or level or type or social norm; not abnormal
3. adj. being approximately average or within certain limits in e.g. intelligence and development
4. adj. in accordance with scientific laws
5. n. something regarded as a normative example