Lily definitely referred to the marauders as her boys, the boys, these boys, etc. Just boys all the time.

At first when she would walk into a room and say, "There are my boys", or "Great my boys are here!", they'd all say,"no Evans we are  independent MEN, we are not BOYS, we don't belong to anyone, we are a SOCIETY OF INDEPENDENT STRONG MEN".

Eventually when she walked into the common room saying," Where are my boys", they would all instinctively chime in," In here", and accepted their position as Lily's boys.

It caught on with the other students and teachers, if they wanted to talk to all of them they would say," Lily and the  boys, do you have a second?".
When Mcgonagll called roll mentally she went, Longbottom,Evans, Evans boys. It was their most well known title and it stuck through their adult life too.

Just Imagine Lily hosting Christmas dinner with the weaslys and calling in "her boys" and this extended to Ron and Harry as well. Of course the other weaslys wanted the same treatment and their father admitted that when they were at hogwarts he was considered one of Evans boys starting sixth year.

By the time the weaslys and Harry had family's of their own lily had about 59 boys of her own, running around doing her bidding. Neville was of course also part of her boys and Ginny and Hermione were in partial control and were to inherit the roll, because although James and Lily had about 10 boys,( they often lost count) they did not have any daughters biologically, Hermione and Ginny were as much as family as Harry and his brothers were.

And when Harry and Ginny married, Ginny was a daughter in law and technically so was Hermione because she married Ron who is Ginny's sister, "yes it makes sense James now shut up I'm brilliant"