WordWeb Online

1. Incapable of adapting or changing to meet circumstances
   "an inflexible law";
   - rigid, unbending
    
2. Incapable of change
   "a man of inflexible purpose"
    
3. Not making concessions
   "took an inflexible stance in the peace talks";
   - uncompromising, sturdy, down-the-line [informal]
    
4. Resistant to being bent
   "an inflexible iron bar"; "an inflexible knife blade"

See also: adamant, adamantine, brassbound, die-hard, fossilised [Brit], fossilized, hard-core, hardline, hard-line, inelastic, inexorable, intransigent, ironclad, muscle-bound, ossified, rigid, rock-ribbed [N. Amer], semirigid, stiff, unadaptable, unbudgeable

Antonym: conciliatory, flexible

Encyclopedia: Inflexible