Definition of "irrational" []

• Not endowed with reason. (adjective)
• Affected by loss of usual or normal mental clarity; incoherent, as from shock. (adjective)
• Marked by a lack of accord with reason or sound judgment: an irrational dislike. (adjective)
• Being a syllable in Greek and Latin prosody whose length does not fit the metric pattern. (adjective)
• Being a metric foot containing such a syllable. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "They are not irrational numbers according to Wittgenstein's criteria, which define, Wittgenstein interestingly asserts, “precisely what has been meant or looked for under the name ˜irrational number™” (PR §191)."
• "Although Greenspan's use of the term "irrational exuberance" has been referred to quite often since the global financial meltdown of 2008, if you really want to see what "irrational exuberance" looks like you should start with this clip from Busby Berkeley's 1933 movie musical, 42nd Street in which Ginger Rogers sings one verse of "We're In The Money" in pig latin:"
• "I put it down to what I call the irrational power of television."