What does hypothesis mean?

Generally hypothesis is a well-tested explanation. But it is not the same as theory. A hypothesis also is a proposal intended explain certain facts or observations. A hypothesis has aim of verify something scientificly too. A hypothesis should be base on a theory but it must be more tested than a theory. According to NASA a hypothesis is possible explanation of an experiment’s results. Creating hypothesis is a step of scientific method too. However hypothesis is more certain than a theory.

quest.nasa.gov/projects/flies/vocab.html
http://www.dana-farber.org/can/dictionary/?index=h
http://wordnet.princeton.edu/perl/webwn?s=hypothesis&o2=&o0=1&o7=&o5=&o1=1&o6=&o4=&o3=&h=000http://en.wikipedia.org/wiki/Hypothesis