Synonyms:
- adamant,
- adamantine,
- aloof,
- arrowlike,
- cast-iron,
- constant,
- dead straight,
- direct,
- distant,
- dour,
- even,
- firm,
- fixed,
- flat,
- flinty,
- fundamentalist,
- grim,
- hard,
- hard-core,
- hidebound,
- horizontal,
- immovable,
- immutable,
- implacable,
- impliable,
- in a line,
- inductile,
- inelastic,
- inexorable,
- inextensible,
- inextensile,
- inextensional,
- inflexible,
- insociable,
- intractable,
- intractile,
- intransigent,
- iron,
- ironbound,
- ironclad,
- ironhanded,
- irreconcilable,
- irresilient,
- level,
- lineal,
- linear,
- loyal,
- muscle-bound,
- nonelastic,
- nonstretchable,
- obdurate,
- obstinate,
- offish,
- orthodox,
- procrustean,
- purist,
- puristic,
- puritan,
- puritanic,
- rectilineal,
- rectilinear,
- relentless,
- reserved,
- right,
- rigid,
- rigorist,
- rigoristic,
- rigorous,
- rock-ribbed,
- rockbound,
- ruler-straight,
- set,
- settled,
- single-minded,
- smooth,
- sot,
- standoffish,
- staunch,
- steadfast,
- steady,
- steely,
- stern,
- stiff,
- straight,
- straight-cut,
- straight-front,
- straight-side,
- straightlaced,
- straitlaced,
- streamlined,
- stubborn,
- true,
- unaffected,
- unalterable,
- unapproachable,
- unbent,
- unbowed,
- unbroken,
- unchangeable,
- uncommunicative,
- uncompromising,
- uncurved,
- undeflectable,
- undeflected,
- undeviating,
- undistorted,
- unextendible,
- unextensible,
- unflappable,
- unflexible,
- ungiving,
- uninterrupted,
- unlimber,
- unmalleable,
- unmoved,
- unpliable,
- unpliant,
- unrelenting,
- unshaken,
- unswayable,
- unswerving,
- untractable,
- unturned,
- unyielding,
- upright,
- vertical,
- withdrawn