Words / B2

i-RASH-uh-nl/ɪˈræʃənl/

Irrational means not based on reason: an irrational fear; irrational numbers (maths). Rational is the opposite. An irrational fear of the oral still needs a plan. Psychology and maths (√2). Do not call a feeling you disagree with irrational without argument.

Meaning

Not based on reason or clear thinking.

Examples

• “An irrational fear of the oral still needs a study plan, tutors said.”
• “Show that √2 is irrational, which is the number-theory sense.”

Good to know

an irrational fear / decision; an irrational number. Opposite: rational. Psychology and maths. Unreasoned — not merely unusual.

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