One of things my late friend Marshall and I would discuss was the need for uniformity in how genealogists used certain words in print. Those words were: Probable, Possible, and Likely. Many genealogists use these terms but they may mean different things to different people. I try to use the terms as this [Marshall's designations]:
Probable: 75% sure of the relationship
Likely: 50% sure of the relationship
Possible: 25% sure of the relationship
Next time you are reading a genealogical article see how many times you spot these terms. What do you think they mean?