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.
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.
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.
a. Relating to or characterized by average intelligence or development.
b. Free from mental illness; sane.
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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.