How ghosts appear to be immaterial entities (8)

I believe the answer is:

nobodies

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'entities' is the definition.
(nobody is a kind of entity)

I don't understand how the rest of the clue works.

(Other definitions for nobodies that I've seen before include "Unimportant people" , "Insignificant people" , "People without importance or authority" , "Ciphers" .)

I've seen this clue in The Irish Times.

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