Something that not only could happen, but it can be believable that it can or could happen.
Although the idea of a cat learning to play the piano is Plausable, it's still unlikely that it would happen without extensive training and some innate talent.
A condition in which a subject can safely and believeably deny knowledge of any particular truth that may exist because the subject is deliberately made unaware of said truth so as to benefit or shield the subject from any responsibilityassociated through the knowledge of such truth.
The CIA black ops division undertakes dangerous and usually what would be considered illegal missions that are not officially sanctioned by the US administration so that the administration, which usually benefits from such missions, can safely dissavow any knowledge of them in the event of their publically uncovered success or failure. The administration is in the position of plausible deniability towards the CIA's actions.
A transitioned transgendered person who, to people uninformed, appears to have been born the gender they describe themselves as.
"Wow. You look very passable! I would have never guessed you were born a man. *heart* *heart*" - Russ lindquist, video blogger, trolling an Australianprostitute in his video SFTU 854.