First Known Use: 14th century
Dictionary
1rational
adjective ra·tio·nal \ˈrash-nəl, ˈra-shə-nəl\
: based on facts or reason and not on emotions or feelings
: having the ability to reason or think about things clearly
Full Definition of RATIONAL
1
a : having reason or understanding b : relating to, based on, or agreeable to reason : reasonable <a rational explanation> <rational behavior>
2
: involving only multiplication, division, addition, and subtraction and only a finite number of times
3
: relating to, consisting of, or being one or more rational numbers <a rational root of an equation>
— ra·tio·nal·ly adverb
— ra·tio·nal·ness noun
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Origin of RATIONAL
Middle English racional, from Anglo-French racionel, from Latin rationalis, from ration-, ratio
Related to RATIONAL
- Synonyms
- intelligent, reasonable, reasoning, thinking
- Antonyms
- irrational, nonrational, nonthinking, unintelligent, unreasonable, unreasoning, unthinking
2rational
noun
Definition of RATIONAL
: something rational; specifically : rational number
First Known Use of RATIONAL
1606
RATIONAL Defined for Kids
rational
adjective ra·tio·nal \ˈra-shə-nəl\
Definition of RATIONAL for Kids
1
: having the ability to reason <Humans are rational creatures.>
2
: based on or showing reason <rational thinking> <a rational decision>
— ra·tio·nal·ly adverb
Medical Dictionary
rational
adjective ra·tio·nal \ˈrash-nəl, -ən-əl\
Medical Definition of RATIONAL
1
a : having reason or understanding b : relating to, based on, or agreeable to reason <a rational explanation> <rational behavior>
2
: using medical treatments based on reason or general principles—used especially of an ancient school of physicians; compare empirical 1a
—ra·tio·nal·ly \-ē\ adverb
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