Conforming with, adhering to, or constituting a norm, standard, pattern, level, or type; typical: normal room temperature; one's normal weight; normal diplomatic relations. Biology Functioning or occurring in a natural way; lacking observable abnormalities or deficiencies. Chemistry Designating a solution having one gram equivalent weight of solute per liter of solution. Chemistry Designating an aliphatic hydrocarbon having a straight and unbranched chain of carbon atoms. Mathematics Being at right angles; perpendicular. Mathematics Perpendicular to the direction of a tangent line to a curve or a tangent plane to a surface. Relating to or characterized by average intelligence or development. Free from mental illness; sane. Something normal; the standard: scored close to the normal. The usual or expected state, form, amount, or degree. Correspondence to a norm. An average. Mathematics A perpendicular, especially a perpendicular to a line tangent to a plane curve or to a plane tangent to a space curve.