invariable
single
abiding
accordant
alike
automatic
balanced
blah
broken-record
ceaseless
changeless
chattering
consistent
consonant
constant
continual
continuing
continuous
correspondent
drearisome
dreary
dry
dryasdust
dull
durable
dusty
enduring
equable
equal
even
everlasting
firm
fixed
flat
frozen
harping
homogeneous
humdrum
immobile
immutable
incessant
incommutable
inconvertible
indefeasible
inert
insusceptible of change
intact
intransmutable
inviolate
irretrievable
irreversible