rigid (n.)
- adamant
- buckram
- close
- constant
- dour
- even
- express
- faithful
- fine
- firm
- fundamentalist
- grim
- hard
- immovable
- iron
- ironclad
- lasting
- literal
- minute
- narrow
- nice
- orthodox
- particular
- pat
- permanent
- pinpoint
- prim
- purist
- puritan
- religious
- set
- solid
- sound
- square
- stable
- starch
- static
- stern
- stiff
- stout
- strict
- stringent
- strong
- tense
- tight
- tough
rigid (adj.)
- abiding
- accurate
- adamant
- adamantine
- attentive
- austere
- buckram
- careful
- cast-iron
- changeless
- close
- conscientious
- constant
- continuing
- correct
- critical
- delicate
- demanding
- detailed
- determined
- direct
- dogged
- dour
- draconian
- durable
- enduring
- even
- exact
- exacting
- exigent
- express
- exquisite
- faithful
- fine
- finical
- finicky
- firm
- fixed
- flinty
- frozen
- fundamentalist
- fussy
- grim
- hard
- hard-core
- hard-line
- harsh
- headstrong
- hidebound
- immobile
- immotile
- immovable
- immutable
- implacable
- inelastic
- inerrable
- inerrant
- inexorable
- infallible
- inflexible
- infrangible
- intact
- intransigent
- inviolate
- iron
- ironclad
- irreconcilable
- irremovable
- lasting
- literal
- mathematical
- meticulous
- microscopic
- minute
- mulish
- muscle-bound
- narrow
- nice
- obdurate
- obstinate
- orthodox
- painstaking
- particular
- pat
- permanent
- perpetual
- persevering
- persistent
- pigheaded
- precise
- prim
- procrustean
- punctilious
- punctual
- puritanic
- quiescent
- refined
- relentless
- religious
- remaining
- resolute
- resolved
- rigorous
- rock-ribbed
- rockbound
- rodlike
- scientific
- scrupulous
- set
- severe
- single-minded
- solid
- sound
- square
- stable
- standpat
- starchy
- static
- stationary
- staunch
- steadfast
- steely
- stern
- stiff
- stilted
- stout
- straightlaced
- strait-laced
- straitlaced
- strict
- stringent
- strong
- stubborn
- sturdy
- subtle
- sustained
- taut
- tenacious
- tense
- thorough
- tight
- torpid
- tough
- unadaptable
- unaffected
- unalterable
- unaltered
- unbending
- unbreakable
- unchangeable
- unchanged
- unchanging
- unchecked
- uncompromising
- undeviating
- unerring
- unfading
- unfailing
- unmovable
- unmoved
- unmoving
- unqualified
- unrelaxed
- unrelenting
- unswerving
- unvaried
- unvarying
- unwavering
- unyielding
