It is a Latin locution that means "At the door" and that means that soon it will happen, that soon it will happen. That will happen immediately, that it will soon happen. Next to start .
It is Latin, meaning "at the gates, before [our] doors" . It is used when a situation is of imminent resolution, when an important moment is approaching. The origin is in the Carthaginian invasion under Hannibal of Rome during the third century BC. C. , when the senate demanded urgent defense measures because "Hannibal ad portas" (" "Hannibal is at the gates!" ) , seeing his army on the banks of the river Anio, about 5 kilometers from the Roman walls. Then the phrase remained as a catchphrase used by the senators whenever it was urgent to take a measure. See "Carthago delenda est" .
It means that something is going to happen, something that has to do with nature
In the doors. It is used as a work that is rejected and not accepted.
different meaning: on the front door, close to the exit of a site. and is used figuratively to say that it is nearly finished an activity, work, career, course... ( I find ad portas to be lawyer, physician, specialist, etc. )