irrational
adjectiveUK /ɪˈræʃ.ən.əl/
US /ɪˈræʃ.ən.əl/
Not thinking in a clear, sensible way.
She had an irrational fear of butterflies.
RELATED WORDS
OTHER MEANINGS
2. In math, a number that cannot be written as a simple fraction.
The square root of two is an irrational number.
3. Not based on reason or clear thinking.
His irrational decision surprised everyone.
4. Lacking normal mental clarity.
The illness left him temporarily irrational.