(ˈ)in, ən+ adjective
Etymology: Middle English, from Latin inflexibilis, from in- in- (I) + flexibilis flexible — more at flexible
1. : not capable of being bent : rigid
2. : firm in will or purpose : unyielding , inexorable
a man of upright and inflexible temper — Joseph Addison
inflexible purpose
3. : incapable of change : unalterable , immutable
arbitrary and inflexible rulings of bureaucracy — Edward Shils
Synonyms: see stiff