Definition

1. Adjective:
   • Lacking any logical justification or cause: Describes something that occurs or exists without a sensible, understandable, or rational basis.
   • Not possessing the ability to reason: Describes a being or entity that is incapable of logical thought.
   • Not characterized by or using reason: Describes actions, feelings, or behavior that are devoid of logical thought or rationality.

Usage Examples

• Adjective:
  • The sudden, reasonless hostility between the old friends puzzled everyone.
  • He was filled with a reasonless anxiety that had no identifiable source.
  • The philosopher argued that animals are not reasonless creatures but have their own forms of intelligence.

Advanced Usage

• "reasonless fear": An irrational fear that arises without a logical cause.
  • She was plagued by a reasonless fear of open spaces.
• "reasonless act": An action performed without any logical motive or forethought.
  • The vandalism was a reasonless act of destruction.

Variants and Related Words

• Reason (n): The power of the mind to think, understand, and form judgments logically.
• Reason (v): To think, understand, and form judgments logically.
• Reasonable (adj): Having sound judgment; fair and sensible.
• Reasonably (adv): In a fair and sensible manner; to a moderate or acceptable degree.
• Reasoning (n): The process of thinking about something logically.

Synonyms

• Senseless: Lacking common sense; wildly foolish.
• Causeless: Having no cause or origin.
• Irrational: Not logical or reasonable.
• Arbitrary: Based on random choice or personal whim, rather than any reason or system.
• Mindless: Acting or done without justification or concern for the consequences.

Antonyms

• Reasonable: Based on good sense.
• Rational: Based on or in accordance with reason or logic.
• Justified: Having, done for, or marked by a good or legitimate reason.
• Sensible: Done or chosen in accordance with wisdom or prudence; practical.

Related Phrases and Idioms

• Without rhyme or reason: Having no discernible logic or explanation. (This idiom is a close conceptual synonym for the sense of "lacking justification").
  • His decision seemed to be made without rhyme or reason.

Adjective

1. having no justifying cause or reason
   • a senseless, causeless murder
   • a causeless war that never had an aim
   • an apparently arbitrary and reasonless change
2. not endowed with the capacity to reason
   • a reasonless brute
3. not marked by the use of reason
   • mindless violence
   • reasonless hostility
   • a senseless act