one who vigorous posts political propaganda and petitions in an effort to affect change in the world without leaving the comfort of the computer screen
No one ever shows up for our Slacktivists United meetings.
A great form of slacktavism is changing your facebook picture to support a cause with out actually doing anything that will make a difference. You are one great slacktavist.
The act of participating in obviously pointless activities as an expedient alternative to actually expending effort to fix a problem.
Signing an email petition to stop rampant crime is slacktivism. Want to really make your community safer? Get off your ass and start a neighborhood watch!