Definition of "layman"

Layperson, someone who is not an ordained cleric or member of the clergy.  examples

(by extension) Someone who is not a professional in a given field.  examples

A common person.  examples

A person who is untrained or lacks knowledge of a subject.  quotations  examples

Lay-sister or lay-brother, person received into a convent of monks, following the vows, but not being member of the order.  examples