Comet and Meme

Comet noun - (astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit.

Meme and comet are semantically related. In some cases you can use "Meme" instead a noun "Comet".

Meme noun - A cultural unit (an idea or value or pattern of behavior) that is passed from one person to another by non-genetic means (as by imitation).

Comet and meme are semantically related. You can use "Comet" instead a noun "Meme".