Or alternatively she was an unmarried daughter still living at home with her parents? The other interpretations seem a bit over-complicated - why would the priest or the bride herself use an obscure Latin term to describe a housemaid? Modern and medieval 'church Latin' doesn't always have the same range of meaning as classical Latin.
I'm not completely convinced I have the correct Mary as her parents were born ,died and were married in Dungannon but as her father had been a soldier , the children were born all over the place Mary being born in Lincolnshire UK ,it's been a long haul finding the BMDs and the spelling of the surname is another headache depending on how it sounded to the registrar