unpliant
/(ˌ)ʌnˈplʌɪənt/adjective
1Not easily influenced or persuaded; obstinate, stubborn; unconforming.
2Not easily bent or changed in shape; stiff, rigid, inflexible.
3Not adaptable to different purposes, changing circumstances, etc.; not showing adaptability or versatility.
Origin
Mid 16th century; earliest use found in Robert Record (c1512–1558), mathematician. From un- + pliant.