unreasonable

UK: ʌnˈriːz(ə)nəb(ə)l | US: ʌnˈriːz(ə)nəb(ə)l

Definition

  1. adj. not guided by or based on good sense or logic

  2. adj. exceeding reasonable limits; excessive

Structure
un <not>reason <logic>able <capable of>
Etymology

The word "unreasonable" combines three morphemes:

  1. "un-" (Old English "un-"), a prefix meaning "not," negates the following root.
  2. "reason" (Latin "rationem," via Old French "raison"), meaning "logic" or "judgment."
  3. "-able" (Latin "-abilis"), a suffix indicating capability.
    Originally, "reasonable" (Middle English) meant "endowed with reason." Adding "un-" flipped the meaning to "lacking logic" or "excessive." Over time, it evolved to describe actions or demands beyond rational limits.
Examples

  1. The landlord’s rent increase seemed unreasonable to the tenants.

  2. It’s unreasonable to expect perfection from a beginner.

  3. She refused to tolerate his unreasonable behavior.

  4. The judge dismissed the claim as unreasonable.

  5. His demands grew increasingly unreasonable over time.