Origin: Latin suffix -able
Improbable has 4 different meanings across 1 category:
not likely to be true or to occur or to have occurred
"legislation on the question is highly unlikely"
"an improbable event"
having a probability too low to inspire belief
"The odds of finding that exact lottery ticket in my attic are so improbable that I can't even believe it's possible."
Not likely to be true.
"It is highly improbable that he actually forgot our anniversary given how well he remembers everything else."