ra·tio·nal /ˈræʃnəl, ˈræʃənḷ/
 (a.)理性的,合理的,推理的有理數


 ra·tio·nal /ˈræʃnəl, ənḷ/ 形容詞



 rational
 有理


 Ra·tion·al a.
 1. Relating to the reason; not physical; mental.
    Moral philosophy was his chiefest end; for the rational, the natural, and mathematics . . . were but simple pastimes in comparison of the other.   --Sir T. North.
 2. Having reason, or the faculty of reasoning; endowed with reason or understanding; reasoning.
    It is our glory and happiness to have a rational nature.   --Law.
 3. Agreeable to reason; not absurd, preposterous, extravagant, foolish, fanciful, or the like; wise; judicious; as, rational conduct; a rational man.
 4. Chem. Expressing the type, structure, relations, and reactions of a compound; graphic; -- said of formulae. See under Formula.
 Rational horizon. Astron. See Horizon, 2 (b).
 Rational quantity Alg., one that can be expressed without the use of a radical sign, or in exact parts of unity; -- opposed to irrational or radical quantity.
 Rational symptom Med., one elicited by the statements of the patient himself and not as the result of a physical examination.
 Syn: -- Sane; sound; intelligent; reasonable; sensible; wise; discreet; judicious.
 Usage: Rational, reasonable. Rational has reference to reason as a faculty of the mind, and is opposed to irrational; as, a rational being, a rational state of mind, rational views, etc. In these cases the speculative reason is more particularly, referred to. Reasonable has reference to the exercise of this faculty for practical purposes, and means, governed or directed by reason; as, reasonable desires or plans; a reasonable charge; a reasonable prospect of success.
 What higher in her society thou find'st
 Attractive, human, rational, love still.   --Milton.
    A law may be reasonable in itself, although a man does not allow it, or does not know the reason of the lawgivers.   --Swift.


 Ra·tion·al, n. A rational being.

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 rational
      adj 1: consistent with or based on or using reason; "rational
             behavior"; "a process of rational inference";
             "rational thought" [ant: irrational]
      2: of or associated with or requiring the use of the mind;
         "intellectual problems"; "the triumph of the rational over
         the animal side of man" [syn: intellectual, noetic]
      3: capable of being expressed as a quotient of integers;
         "rational numbers" [ant: irrational]
      4: having its source in or being guided by the intellect
         (distinguished from experience or emotion); "a rational
         analysis"