to fill up what is still missing, until a measure, a place, or an obligation is complete
Picture a container that is not quite full, or a gap in a line of people. This verb is about topping that up: not filling from empty, but adding whatever is still missing until nothing is short. The first part of the Greek word does not mean "again", so it never describes refilling something; it points upward, to filling a thing right to the top.
The same picture stretches in several directions:
- friends who bring what a whole church could not send
- a sick messenger who supplies the help others were unable to give
- someone occupying the seat where an untrained listener belongs
- an obligation carried through to the end, so that the law of Christ is done in full
- a prophecy that finds its complete match in what people are actually doing
The picture works just as well for something bad. When Paul says that opponents of the message are always filling up their sins, he means a measure is being topped up toward the brim, and that judgment arrives when it is full.
Set beside the broad verb "to fill" (πληρόω), which fills a space or a person completely, this word keeps its eye on the shortfall: what was missing has now been made good. A close relative adds the idea of supplying on top of what is already there (προσαναπληρόω), and another describes filling up a lack on someone else's behalf (ἀνταναπληρόω).