Hitler explained his frustrations in terms of a Jewish conspiracy.
I am familiar with the idiomatic meaning of the phrase "in terms of" (Like This film offers nothing in terms of satisfactory entertainment.) I suppose this idiomatic meaning is not used in the sentence above. What is the exact meaning of that sentence? Hitler explained his frustrations in the point of view of a Jewish conspiracy. Or Hitler explained his frustrations with words/concepts of a Jewish conspiracy.
"In terms of X" means "related to X", "having to do with X", "in the context of X", etc. Exactly how X relates depends on the context.
In this case, the writer means that Hitler explained that the cause of his problems -- I presume the writer meant Germany's problems as opposed to Hitler's personal problems, though I'd have to read the larger context to say -- was a Jewish conspiracy.
Note that if the writer had written, say, "Hitler explained his frustrations in terms of Freudian psychology" the meaning would be quite different. He would likely mean, not that Freudian psychology caused his frustrations, but rather that Freudian psychology provided a basis for understanding his frustrations. That's an example of what I mean when I say that it depends on context.
The usage in the "Hitler" sentence is really quite similar to the usage in the "film" sentence. In the "Hitler" sentence "in terms of" identifies what causes the frustrations; in the "film" sentence "in terms of" identifies what is (not) offered.
(Do I need to add that I am not agreeing with Hitler when describing his opinion about the Jews and Germany? It occurs to me that if I were ever to run for office and my opponent found this post, he could pull sentences out of context to make me sound anti-Semitic. :-0 )
"In terms of" is about point of view. It means that you are not considering something holistically; instead, you are viewing it from a certain perspective.
In this case, something like : "Hitler explained his frustrations from the perspective of assuming a Jewish conspiracy."
