an oblique way of announcing an absolute deadline, often by a person wishing to protect their own time from further encroachment by an unfettered task or inconsiderate colleague, as in “We have to finish this presentation by this afternoon since I have a hard stop at 4 pm”; the cause for the hard stop may be expressed but can also be left unspoken, creating an air of intrigue as to what obligation is so pressing; indicates that after the time mentioned the listeners are on their own, because the person stating he has a hard stop sure isn’t going to be around to help after that