There's not one, not two, but three definitions of the word in current usage.
1. Original Definition
The first is Richard Dawkin's original definition from the 1976 Selfish Gene.
In this 2013 presentation he summarises the concept:
Memes can be good ideas, good tunes, good poems as well as drivelling mantras. Anything that spreads by imitation - as genes spread by bodily reproduction or viral infection - is a meme
2. Internet Meme
This original usage has been transformed to refer to concepts found on the Internet that are easily copied, but also easily modified and re-generated.
Later in the same presentation, Richard Dawkins explains that this is a different definition.
But the very idea of the meme has itself mutated and evolved in a new direction. An Internet meme is a hijacking of the original idea. Instead of mutating by random chance before spreading by a form of Darwinian selection, Internet memes are altered deliberately by human creativity.
In a 2013 Wired interview about the same presentation, he explains the two meanings are related:
How do you feel about your word meme being reappropriated by the internet?
The meaning is not that far away from the original. It's anything that goes viral. In the original introduction to the word meme in the last chapter of The Selfish Gene, I did actually use the metaphor of a virus. So when anybody talks about something going viral on the internet, that is exactly what a meme is and it looks as though the word has been appropriated for a subset of that.
3. Image Macros
A third concept is sometimes called an Image Macro, and refers to an image (generally a photo) with text superimposed on it (generally in the Impact font).
Image macros - at least the successful ones - are examples of Internet memes. They are often directly referred to as "memes".
This "confusion" between image macros and memes angers some linguistic prescriptivists:
Such a position misses the point in two ways:
There is no official authority on the English language. If many people use the word "meme" to refer to image macros, then that is what the word means.
If there were an authority on the official definition of meme, it must surely be Richard Dawkins, and we can see the definition that the prescriptivists are using does not precisely match Dawkin's original definition.
In summary, it is not wrong to refer to any of these concepts as memes:
- concepts widely shared orally or in print and modified by accident.
- concepts widely shared through social media and deliberately modified with image editing tools.
- image macros - images with writing on them, following a common style or template.