A Dawkinsian "meme" is like an idea-unit that can take hold and thrive in the landscape of imagination, developing into culture or philosophy if it spreads widely enough.
Good definition! I'll often say it is a "primary unit of cultural exchange." I consider a lot of things memes: internet memes of course, songs, scenes from movies, plot tropes, characters, basically any bit of culture that can be encapsulated and identified as a distinct entity.