inflexible

/ɪnˈflɛksəbəl/
adjective
  1. Unwilling to change opinions, plans, or decisions; stubborn.
    • My boss is inflexible about deadlines, so we always finish on time.
    • She was inflexible in her belief that hard work always pays off.
    • The teacher's inflexible grading policy left no room for extra credit.
  2. Not able to be bent or changed physically; stiff.
    • The hiker's boots had inflexible soles that made walking on rocks uncomfortable.
    • An inflexible ruler cannot measure curved surfaces accurately.
    • The plastic became inflexible and brittle after years in the sun.
  3. Not able to be changed or adapted; fixed.
    • The schedule was inflexible, leaving no time for breaks.
    • The contract had inflexible terms that could not be renegotiated.
    • Inflexible rules can sometimes cause more problems than they solve.