- not logical or reasonable；not endowed with the power of reason.
- an irrational number or quantity; a surd.
- 1. not logical or reasonable irrational feelings of hostility
- ▪ not endowed with the power of reason.
- 2. (of a number, quantity, or expression) not expressible as a ratio of two integers, and having an infinite and non-recurring expansion when expressed as a decimal. Examples of irrational numbers are the number π and the square root of 2.
- 1. an irrational number or quantity; a surd.