The adjective "posh", particularly in Britain, is used by people not from smart backgrounds to describe either people whom they believe to be upper class or when they are describing places or things which they believe are associated with the upper class. Often this is used inaccurately. A person from a non-smart background would probably regard a restaurant that provided elaborately folded napkins as 'posh', when in fact a person from a smart background would either laugh or smile to themselves at the exaggerated attempt to appear genteel.

People aspiring to be 'posh' invitably fail in the first instance as they will actually use the term 'posh' in an attempt to describe an event ('function' they would probably say) which they believe will afford them some social cachet. A person from a smart background will usually speak more directly and not use grandiose words. They would also never seek to draw attention to themselves as being smart (unless of course they are insecure).