meme
/mēm/

noun

1. A unit of cultural information, such as a cultural practice or idea, that is transmitted verbally or by repeated action from one mind to another.

2. Any unit of cultural information, such as a practice or idea, that is transmitted verbally or by repeated action from one mind to another.

3. A self-propagating unit of cultural evolution having a resemblance to the gene (the unit of genetics).

The American Heritage® Dictionary of the English Language, 5th Edition • More at Wordnik