Nor"mal (?), a. [L. normalis,
fr. norma rule, pattern, carpenter's square; prob. akin to
noscere to know; cf. Gr. &?; well known, &?; gnomon, also,
carpenter's square: cf. F. normal. See Known, and cf.
Abnormal, Enormous.]
1. 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.
Deviations from the normal type.
Hallam.
2. (Geom.) According to a square or
rule; perpendicular; forming a right angle. Specifically: Of or
pertaining to a normal.
3. (Chem.) Standard; original; exact;
typical. Specifically: (a) (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.
(b) (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. (c) (Organ. Chem.)
Denoting that series of hydrocarbons in which no carbon atom is
united with more than two other carbon atoms; as, normal
pentane, hexane, etc. Cf. Iso-.
Normal equations (Method of Least
Squares), a set of equations of the first degree equal in
number to the number of unknown quantities, and derived from the
observations by a specified process. The solution of the normal
equations gives the most probable values of the unknown
quantities. -- Normal group (Geol.),
a group of rocks taken as a standard. Lyell. --
Normal place (of a planet or comet)
(Astron.), the apparent place in the heavens of a planet
or comet at a specified time, the place having been determined by a
considerable number of observations, extending perhaps over many
days, and so combined that the accidental errors of observation have
largely balanced each other. -- Normal school,
a school whose methods of instruction are to serve as a model for
imitation; an institution for the training of teachers.
Syn. -- Normal, Regular, Ordinary.
Regular and ordinary are popular terms of well-known
signification; normal has now a more specific sense, arising
out of its use in science. A thing is normal, or in its
normal state, when strictly conformed to those principles of
its constitution which mark its species or to the standard of a
healthy and natural condition. It is abnormal when it departs
from those principles.
Nor"mal (?), n. [Cf. F. normale,
ligne normale. See Normal, a.]
1. (Geom.) Any perpendicular.
2. (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.
&fist; The term normal is also used to denote the distance
along the normal line from the curve to the axis of abscissas or to
the center of curvature.
