unadaptable
adamant
adamantine
aloof
arrowlike
cast-iron
constant
dead straight
direct
distant
dour
even
firm
fixed
flat
flinty
formal
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
austere
dauntless
disdainful
imperious
indomitable
masterful
morose
resolute
rigid
steadfast
steely
stubborn
undeviating
unflinching
unforgiving
amending
apprehending
ascending
attending
befriending
bending
blending
commending
comprehending
condescending
contending
defending
depending
descending
ending
expending
extending
fending
impending
intending
lending
mending
misspending
offending
overextending
pending
portending
pretending
recommending
rending
sending
spending
suspending
tending
transcending
trending
unending
vending
wending