layman

Short definition from Wiktionary

Noun

1. 1
   Layperson, someone who is not an ordained cleric or member of the clergy.
2. 2
   Someone who is not a professional in a given field.
3. 3
   A common person.
4. 4
   A person who is untrained or lacks knowledge of a subject.
5. 5
   Lay-sister or lay-brother, person received into a convent of monks, following the vows, but not being member of the order.

Proper noun

1. 1
   A surname.