The word passable is an adjective. It describes something that can be passed.
unpassable
Is it passable fair fine good excellent splendid
not passable, blocked
It is not passable there is no evolving for it
Some looking like a woman
respectable, tolerable, acceptable
A possible prefix for "passable" is "im-," which would change the meaning to "impassable," meaning unable to be passed through or crossed. Prefixes are added to the beginning of a word to modify its meaning. In this case, adding "im-" changes the word from being able to be passed to not being able to be passed.
After I received a failing mark on my English paper, I spoke to the teacher and explained that, while I didn't think I deserved an "A", the work I did was certainly passable.
A passable law might be:a law that is minimally acceptable, ora bill that is able to be passed by a legislature to become a law, i.e., one with sufficient support to be passed.
He plays a barely passable saxophone.
A mediocre grade is one that is barely passable.