Plain English Meaning
It's an AD requirement that has to be done over and over on a set schedule, not just once. You complete it, then keep doing it again at the stated interval for as long as you own and operate the aircraft.
Full Definition
In the context of Airworthiness Directives (ADs), a recurrent or continuing action is a required inspection, check, or maintenance task that must be performed repeatedly at specified intervals — such as every flight hour, calendar period, or operating cycle — rather than as a one-time fix. The compliance obligation does not end after the first action; it continues for the life of the aircraft or until the AD is superseded or terminated.
Context Anchor
Seen when reading an Airworthiness Directive to determine whether its requirements are one-time only or must be tracked over time.