Meme
Etymology
Coined by biologist Richard Dawkins in "The Selfish Gene" (1976), from Greek "mīmēma" ("that which is imitated"), deliberately clipped to rhyme with "gene." He proposed it as culture’s analogue to the gene. Flagged as a coinage; note its later narrowing to the online image-macro sense.
noun · /MEEM/
A unit of culture — an idea, behavior, or style — that spreads from person to person by imitation.
What it names
A handle for thinking of culture as something that evolves and replicates like genes — useful well beyond the narrow "internet meme."
Example
Long before the internet, the tune of "Happy Birthday" was a meme, copied faithfully across the whole world.
Related idea
Compare trope, a recurring device or theme; a meme is defined by how it replicates and spreads, not by its role within a single work.