engram

A postulated physical or biochemical change in neural tissue that represents a memory.

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.

A painful, negative mental image representing a past event.

A surname transferred from the given name, a rare variant of Ingram.

an enneagram, a nine-pointed figure.

N-gram, a subsequence.