I'm about to present an exam about ecological interactions in biological control. Although the position of some groups is clear, in the case of parasitoids they are included sometimes as predators, some others as parasites, while sometimes they are included like an own group. For example, in this paper they are included as parasites, but I wanted to know if there is a more recent reference or classification for these groups (Trophic strategies, animal diversity and body size Kevin D. Lafferty and Armand M. Kuris).
I think the wikipedia article defining parasitoids has it right on this one. The term is, and should be flexible and it's definition defined by context. i.e Case by case definitions are made obvious in the literature.
Patently there is no point to trying to draw arbitrary lines of distinction between such vague, and often variable, life histories. In each ecological or ethological study, the terms applied should reflect the facts in the contexts relevant to the matter in question. Such studies need not in all cases use the identical terminology, and there is no reason they should.
This means that you should always describe the life cycle even if you call the organism a parasitoid. There is too much variation between seemingly similar organism life histories to use a strict and specific term.
For those struggling to see the link from the question, they suggest a parasitoid can be measured as a parasite that reduces host fitness to zero:
... they are also quite different from these other parasites, in that, similar to a predator, they must kill their host.
A recent (2015) review on Whiteflies refers to Hymenoptera as parasitoids of Whiteflies because the Hymenoptera are parasitoids as larvae as they kill the Whiteflies and then become free-living adults.