(geometry) A line or vector that is perpendicular to another line, surface, or plane.

(medicine, countable) A person who is healthy, normal, as opposed to one who is morbid.

(slang, countable) A person who is normal, who fits into mainstream society, as opposed to those who live alternative lifestyles.

(countable, uncountable) The usual state.

Adjective "normal" refers to adhering to what is considered natural or regular in a particular field or context, such as in mathematics and various branches of algebra and analysis.

An adjective "normal" represents something that is usual, healthy, not sick or ill, and can also describe someone who is fervently interested or obsessed with a subject.

(to certain norms) (education, of a school) teaching teachers how to teach

(chemistry) Of, relating to, or being a solution containing one equivalent weight of solute per litre of solution.

(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.

(see normal mode) (physics, of a mode in an oscillating system) In which all parts of an object vibrate at the same frequency .

(rail transport, of points) In the default position, set for the most frequently used route.

(geometry) Perpendicular to a tangent of a curve or derivative of a surface.