If your sister is a Sister in the Roman Catholic Church, then she is a votary. People who have devoted their lives to religious service are called votaries.

The noun votary does not necessarily have to be a member of a religious order. A votary can be a person who is a devoted follower of a person or cause. Plenty of history majors are votaries of Abraham Lincoln, but if you prefer more obscurity in your interest in presidents, you may be a votary of William Henry Harrison, who died on his thirty-second day in office — of a cold.

Definitions of votary

n a priest or priestess (or consecrated worshipper) in a non-Christian religion or cult

“a votary of Aphrodite”
show 4 types...
hide 4 types...
vestal virgin
(Roman mythology) one of the virgin priestesses consecrated to the Roman goddess Vesta and to maintaining the sacred fire in her temple
(classical mythology) a priest or votary of Bacchus
(classical mythology) a priestess or votary of Bacchus
Rea Silvia, Rhea Silvia
(Roman mythology) a vestal virgin who became the mother by Mars of the twins Romulus and Remus
Type of:
non-Christian priest, priest
a person who performs religious duties and ceremonies in a non-Christian religion

n one bound by vows to a religion or life of worship or service

“monasteries of votaries
Type of:
a member of a religious order who is bound by vows of poverty and chastity and obedience

n a devoted (almost religiously so) adherent of a cause or person or activity

“the cultured votary of science”
Type of:
adherent, disciple
someone who believes and helps to spread the doctrine of another

Sign up, it's free!

Whether you're a student, an educator, or a lifelong learner, Vocabulary.com can put you on the path to systematic vocabulary improvement.