accompanying
ageless
agreeing
ceaseless
coetaneous
coeval
coexistent
coexisting
coinstantaneous
collateral
concomitant
concurrent
constant
contemporaneous
contemporary
conterminous
continual
continuous
coterminous
dateless
endless
eternal
eterne
ever-being
ever-durable
ever-during
everlasting
everliving
immemorial
incessant
indestructible
infinite
interminable
isochronal
isochronous
never-ceasing
never-ending
nonstop
nonterminating
nonterminous
olamic
perdurable
permanent
perpetual
sempiternal
simultaneous
steady
timeless
unceasing
unending
atom-laser
bluewhite
coextensive
counter-rotating
deep space
electric-eye
infra-ray
it'sa
larbord
longleaf
lower-deck
nail-studded
pencil-thin
precast
prestressed
spearlike
strikedown
tetryon
w-shaped