continual

adjectives

occurring without interruption; chiefly restricted to what recurs regularly or frequently in a prolonged and closely spaced series
"the continual banging of the shutters"
continual
antonym
sporadic
is similar to
repetitive and persistent
"the bluejay's insistent cry"
insistent, repetitive
is similar to
continually repeated over a period of time
"a running joke among us"
running
is similar to
recurring again and again
"perennial efforts to stipulate the requirements"
perennial, recurrent, repeated
is similar to
never-ceasing
"the relentless beat of the drums"
persistent, relentless, unrelenting
is similar to
coming back
"a revenant ghost"
recurring, revenant
`continual' (meaning seemingly uninterrupted) is often used interchangeably with `continuous' (meaning without interruption)
continual
is similar to
continuing in time or space without interruption
"a continuous rearrangement of electrons in the solar atoms results in the emission of light"- James Jeans; "a continuous bout of illness lasting six months"; "lived in continuous fear"; "a continuous row of warehouses"; "a continuous line has no gaps or breaks in it"; "moving midweek holidays to the nearest Monday or Friday allows uninterrupted work weeks"
continuous, uninterrupted