Limiting the scope to humans for now, a meme is a human behavior or trait
acquired through sensory input from other humans, rather than biologically.
A meme has the properties of (1) replication--it can be learned from
others, (2) mutation--it can be created newly or changed, and (3)
competition--humans with different sets of memes compete for resources.
"Memetic" is just the adjective form, so a "memetic system" is just your
collection of memes--the language you speak, the way you hold a fork,
the way you throw a baseball--even things like the rules of baseball and
the design of a fork. These things are all reproduced by communication
and interaction among humans.
The word is a recent coinage by Dawkins in _The Selfish Gene_, and is
only recently appearing in general print, so it will likely be in
dictionaries in a few years.
-- Lee Daniel Crocker <lee@piclab.com> <http://www.piclab.com/lcrocker.html> "All inventions or works of authorship original to me, herein and past, are placed irrevocably in the public domain, and may be used or modified for any purpose, without permission, attribution, or notification."--LDC