Joslyn is a streamlined spelling of Jocelyn, which came to England with the Normans as the male name Joscelin and goes back to a Germanic tribal name, usually explained as "member of the Gauts" or "one of the Geats". It has been used almost exclusively for girls since the 20th century. Joslyn entered the US top 1000 in 2002 and peaked at number 637 in 2011, but it has faded since and ranks number 2732 in 2025.