any real number that cannot be expressed as the ratio of two integers, such as π
irrational number in American English
noun
Math
a number that cannot be exactly expressed as a ratio of two integers
Word origin
[1545–55]This word is first recorded in the period 1545–55. Other words that entered Englishat around the same time include: articulate, caste, insurance, inversion, rounding
Examples of 'irrational number' in a sentence
irrational number
It is an irrational number which, in this politically correct age, seems a trifle pejorative as a label, even if its meaning is strictly mathematical.
Times, Sunday Times (2010)
Pi, the ratio of a circle's circumference to its diameter, is an irrational number, containing an infinite number of digits.
Times, Sunday Times (2010)
The team is composed predominantly of science undergraduates, and one of their drinking games involves reciting irrational numbers.