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# irrational

«irrational» in Mova's school dictionary: **Not based on clear thinking or good reasons (an…** — its meaning for a pupil, its sense in the lessons and examples.

### part of speech

adjective (irrational, more irrational, most irrational)

### meaning for a pupil

1) Not based on clear thinking or good reasons (an irrational fear). [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#m1)

2) (maths) An irrational number cannot be written as a fraction of two whole numbers, and its decimals go on forever without repeating, like pi or the square root of 2. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#m2)

3) Irrational can also describe a creature that cannot reason or think clearly. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#m3)

### sense in the lessons

In everyday life: an irrational fear of spiders or of the dark, a choice made in anger. In maths (later school years): rational numbers are fractions; irrational numbers like pi and the square root of 2 are not. Phrases: irrational fear, irrational behaviour, irrational number.

### examples

- My fear of balloons popping is a bit irrational. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#x1)
- It is irrational to be angry at the rain. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#x2)
- Pi is an irrational number. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#x3)
- The square root of 2 is irrational: its decimals never end or repeat. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#x4)
- He made an irrational decision when he was tired. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#x5)
- Some fears are irrational, but they still feel real. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#x6)
- Jupiter, seeing that Mankind, the only rational creatures, were far outnumbered by the irrational beasts, bade him redress the balance by turning some of the latter into men. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/#x7)

### note

Prefix ir- = not + rational. Double r. Opposite: rational. Math trap: 0.333... (repeating) is rational because it equals one third; only decimals that never end AND never repeat are irrational. 22/7 is close to pi but not equal to it.

### Trees and pragmatics

[Every meaning and example of «irrational» parsed by Mova](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/I/irrational/), each sentence with its dependency tree and frames.