Jocelyn comes from the medieval Old French Joscelin — itself from the Germanic Gauzlin, referring to a member of the Gauts (an East Germanic tribe). It was originally a masculine name; English usage made it predominantly feminine.
Jocelyn entered the U.S. top 1000 in 1942 and has risen steadily. Today it sits in the U.S. top 200.
Jocelyn reduces to one — the number of bright distinct identity.