Pronunciation: (nôr'mul),[key] —adj. 1. conforming to the standard or the common type; usual; not abnormal; regular; natural.
2. serving to establish a standard.
3. Psychol. a. approximately average in any psychological trait, as intelligence, personality, or emotional adjustment.
b. free from any mental disorder; sane.
4. Biol.,Med. a. free from any infection or other form of disease or malformation, or from experimental therapy or manipulation.
b. of natural occurrence.
5. Math. a. being at right angles, as a line; perpendicular.
b. of the nature of or pertaining to a mathematical normal.
c. (of an orthogonal system of real functions) defined so that the integral of the square of the absolute value of any function is 1.
d. (of a topological space) having the property that corresponding to every pair of disjoint closed sets are two disjoint open sets, each containing one of the closed sets.
e. (of a subgroup) having the property that the same set of elements results when all the elements of the subgroup are operated on consistently on the left and consistently on the right by any element of the group; invariant.
6. Chem. a. (of a solution) containing one equivalent weight of the constituent in question in one liter of solution.
b. pertaining to an aliphatic hydrocarbon having a straight unbranched carbon chain, each carbon atom of which is joined to no more than two other carbon atoms.
c. of or pertaining to a neutral salt in which any replaceable hydroxyl groups or hydrogen atoms have been replaced by other groups or atoms, as sodium sulfate, Na_{2}SO_{4}.

—n. 1. the average or mean: Production may fall below normal. 2. the standard or type.
3. Math. a. a perpendicular line or plane, esp. one perpendicular to a tangent line of a curve, or a tangent plane of a surface, at the point of contact.
b. the portion of this perpendicular line included between its point of contact with the curve and the x-axis.

Nor•mal

Pronunciation: (nôr'mul),[key] —n. a city in central Illinois. 35,672.