I first encountered the word on forums. There were some reoccurring themes and motifs that would show up in different members' posts, and those themes and motifs were unique to the forum. Those ideas were called "memes." As I understood it then, a meme was an idea that got spread around a community, and members of that community then made that idea their own.
This definition makes sense in the context of the website knowyourmeme.com. The site is devoted to cataloguing internet trends and explaining their origin. But I've recently discovered that this meaning of "meme" is a transitional definition.
The definition doesn't make as much sense with the website memegenerator.net, where you can go to generate memes. Once, for example, my roommate said to me, "Check out this meme I just made." My response was, "How did you just make a meme?"
Then I realized that "meme" was coming to mean a single image macro, not an overarching theme or idea across the internet.
I decided to consult the Oxford English Dictionary, the mother of all dictionaries, to find out the origin of "meme." I was surprised to find that the word goes back to 1976. It was coined by Richard Dawkins, that unapologetic apologist for atheism. As he first used it, the term meant a culturally inherited trait (e.g., belief in God). Although, I have not read The God Delusion (written by Dawkins), I can't help but think that its popularity and publishing in 2006 led to the rise of the word in its popular, internet context.
I love this. I love how a word's meaning can change so drastically in such a short time. The word went from being scientific jargon to meaning this: