- Lacking in reason or logic
- Not influenced by clear thinking, clarity of mind, or comprehension
- Not based on or in line with the fair examination of facts or supporting evidence
- The judge found the defendant's defense to be irrational, failing to provide a logical argument.
- The lawyer thought the client's decision was irrational due to a lack of clear thinking and understanding.
- The conclusion of the testimony was deemed irrational, as it did not consider all the crucial pieces of evidence.