"Blend of Scott and -lyn"
The name Scottlyn is commonly a female name from the "American" origin.
Scottlyn is a modern American formation that joins Scott, an English and Scottish surname-derived given name, to the -lyn ending used in many twentieth-century girls' names such as Carolyn and Brooklyn. The name first appears in US birth records in 1999, which fits this pattern rather than an older documented naming tradition. No meaning beyond the combination of those two elements is recorded.
The pronunciation of Scottlyn is SKAHT-lin.