What is a strict internal rhyme scheme?

The answer is "The Raven" Internal, or middle, rhymes usually occur within the same line, like the words “lonely” and “only” in line 55.

Allusion and illusion. an allusion is an indirect reference, whereas an illusion is something that is unreal or incorrect. each of the nouns has a related verb form: allude “to refer indirectly to,” and illude (not a very common word), which may mean “to delude or deceive” or “to subject to an illusion.”