The name Fidelia is a girl's name meaning "faithful". Fidelia and discussed in our forums with posts like "Drop you least favourite (girls with middles)".
From the experts:
Fidelia stems from the Latin word Fides, meaning faith. It has the some root as the English word fidelity. Fidelia gained popularity in the mid-19th Century after Beethoven's opera "Fidelio" gave this name cultural and virtuous significance.