Definition of "engram"

I use the word engram to denote this permanent change wrought by a stimulus; the sum of such engrams in an organism may be called its "engram-store," among which must distinguish inherited from acquired engrams.

1921 January, Richard Semon, “II (Engraphic Action of Stimuli on the Individual)”, in Louis Simon, transl., The Mneme‎, Cornell University Library, published 2005, page 24