nor·mal 
(nôrməl)
(nôrməl)adj.
1. 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. Biology Functioning or occurring in a natural way; lacking observable abnormalities or deficiencies.
3. Chemistry
a. Relating to or designating the normality of a solution.
b. Abbr. n Designating an aliphatic hydrocarbon having an acyclic unbranched chain of carbon atoms.
4. Mathematics
a. Being at right angles; perpendicular.
b. Perpendicular to the direction of a tangent line to a curve or a tangent plane to a surface.
5.
a. Relating to or characterized by average intelligence or development.
b. Free from mental illness; sane.
n.
1. The usual, expected, or standard state, form, amount, or degree: Temperatures have been above normal for this time of year.
2. Mathematics A perpendicular, especially a perpendicular to a line tangent to a plane curve or to a plane tangent to a space curve.
[Middle English, from Late Latin normālis, from Latin, made according to the square, from norma, carpenter's square; see gnō- in the Appendix of Indo-European roots.]
normal·ly adv.