What does Unlikely mean?

I don't pretend to have the definitive answer. My more capable predecessors, Reagan, Mosteller and Youtz (1989) decided to find out what probability terms actually mean to people. Here are their results (in % probability):


A couple points of interest to me.

1. The median lower bound for Almost Impossible is 0. Um... that makes no sense. 0 means impossible, no debate.

2. Possible has the largest range. Okay that is not exciting, but that the range is 40-70 is quite interesting. Possible overlaps with Probable, Likely and almost Very Possible.

3. I figured Very Possible and Very Probable wouldn't overlap so much.

4. The 90% lower bound on Almost Certain seems a little low. If it fails 1 time in 10 I wouldn't say it would almost certainly work.