The term layman or layperson originated from the use of the term laity, but over the centuries, changed definition to mean a person who is a non-expert in a given field of knowledge
lay-sister or lay-brother, person received into a convent of monks, following the vows, but not being member of the order
{i} one who is not a member of the clergy; member of the laity; one who does not belong to a particular profession
A layman is a man who is involved with the Christian church but is not a member of the clergy or a monk. In 1932, one Boston layman wrote to Archbishop William O'Connell in support of Father Coughlin
One of the people, in distinction from the clergy; one of the laity; sometimes, a man not belonging to some particular profession, in distinction from those who do