A potentially fatal lapse in subway safety. If you leave the doors between cars slightly open after passing through, then it will create a miniature vortex that will suck anyone stood near the door out into the tunnel.

See also: Fan Death
"John was the first Subway Door Death casualty of the summer season."
by andrewwmorris1 June 28, 2009
very near the end of one's life. (Often an exaggeration.) I was so ill that I was at death's door for three days. The family dog was at death's door for three days, and then it finally died.
dying or very ill He literally was at death's door when a liver became available for transplant.
by lokhad March 30, 2017