Definition of "ectoplasm"

He saw again clearly enough […] the doctor’s consulting room in the Avenida de la Revolución, visited for some drunken reason in the early hours of the morning, macabre with its pictures of ancient Spanish surgeons, their goat faces rising queerly from ruffs resembling ectoplasm, roaring with laughter as they performed inquisitorial operations; […]

1947, Malcolm Lowry, Under the Volcano, New York: Reynal & Hitchcock, page 137

Watching as the woman lifted her skirts and flung out ectoplasm, expelled it into a bowl, then brandished it around at her audience wildly.

2021, Jenni Fagan, Luckenbooth, William Heinemann, page 131

Then came some hollow groanings from inside the cabinet. The Spiritualists sat up expectantly. "That's ectoplasm," said Ogilvy. "It always causes pain on emission."

1925 July – 1926 May, A[rthur] Conan Doyle, “(please specify the chapter number)”, in The Land of Mist (eBook no. 0601351h.html), Australia: Project Gutenberg Australia, published April 2019