Rational may refer to:

• Rational number, a number that can be expressed as a ratio of two integers
• Rational point of an algebraic variety, a point defined over the rational numbers
• Rational function, a function that may be defined as the quotient of two polynomials
• Rational fraction, an expression built from the integers and some variables by addition, subtraction, multiplication and division
• Rational Software, a software company now owned by IBM
• Tenberry Software, formerly Rational Systems, a defunct American software company
• Rational AG, a German manufacturer of food processors
• RationaL, stage name of Canadian hip-hop artist Matt Brotzel
• The Rationals, a former American rock and roll band
• Rational, a personality classification in the Keirsey Temperament Sorter
• Priestly breastplate, called a 'rational' in older Biblical translations, from the Vulgate name for the breastplate: 'rationale'

• Rationality
• Rationale (disambiguation)
• Rationalism (disambiguation)
• Rationalization (disambiguation)