Quick Definition: A unit of cultural ideas, symbols, or practices that transfer and replicate from one mind to another through speech, gestures, rituals, or other cultural activities.
Coined by Richard Dawkins in 1976, the term meme relates to the Greek word mimema for mimic. Memes act as cultural analogues to genes in that they self-replicate and respond to selective pressures, therefore becoming the cultural equivalent of a gene.
The study of memes and how they transfer through cultural generations, and from one culture to another, has spawned “memetics.”
Source: Richard Dawkins, Evolutionary Biology.