means A unit of culture — an idea, image, joke, or behavior — that spreads from person to person, especially the captioned images and viral jokes that replicate across the internet.

from Coined by biologist Richard Dawkins in his 1976 book The Selfish Gene, who wanted a word for ideas that replicate and evolve much like genes do. He shaped it from the Greek 'mimema' (something imitated, related to 'mimeisthai,' to imitate) and deliberately clipped it to rhyme with 'gene.' For decades it lived in academic prose; the internet then took it literally, breeding it into the viral images it now mostly names.