My definition of writer's block is the temporary or chronic inability to produce new work. It's common and it's not a passive condition. For some, it's a temporary problem and they soon move past it. For others, writer's block is extreme and they're unable to write for years and some abandon any attempts. They view their "new" writing as inferior, which may not be true.
Some brilliant person said that writer's block is a loud scream from the unconscious that tells us something is wrong. I often tell people that I once had writer's block and it was the most awful, terrible, horrible hour of my life. My point is that we don't have to suffer from writer's block. We can stop it.
Here's a question to ask ourselves:
What is going on inside me that prevents me from writing?