around-the-clock
ceaseless
consecutive
constant
continual
day-and-night
dogging
endless
free-burning
incessant
never-ending
nonstop
perpetual
persisting
round-the-clock
straight
sustained
unbroken
unceasing
unremitting
ageless
arrowlike
articulated
assiduous
catenated
chattering
coeternal
concatenated
connected
consistent
continued
continuing
continuous
cyclical
dateless
dead straight
diligent
direct
dogged
enduring
eternal
eterne
even
ever-being
ever-durable
ever-during
everlasting
everliving
faithful
featureless
flat
gapless
horizontal
immediate
immemorial
immutable
in a line
inalterable
indefatigable
indestructible
indomitable
industrious
infinite
arduous
fruitless
interminable
inward
monotonous
outward
tranquil
undisturbed
unending
corrupted
disrupted
erupted
interrupted