WordNet sense 1 (maintained at length without interruption or weakening):

sustained

WordNet sense 2 (successive (without a break)):

consecutive, straight

WordNet sense 3 (having the ends united so as to form a continuous whole):

endless

WordNet sense 4 (`continual' (meaning seemingly uninterrupted) is often used interchangeably with `continuous' (meaning without interruption)):

continual

WordNet sense 5 (uninterrupted in time and indefinitely long continuing):

constant, perpetual

WordNet sense 6 (continuing in time or space without interruption):

continuous

WordNet sense 7 (marked by continuous or uninterrupted extension in space or time or sequence):

unbroken