Spanish Meaning: The name Roslyn is a Spanish baby name. In Spanish the meaning of the name Roslyn is: Beautiful; pretty rose. American Meaning: The name Roslyn is an American baby name.In American the meaning of the name Roslyn is: Beautiful; pretty rose.German Meaning: The name Roslyn is a German baby name. In German the meaning of the name Roslyn is: Compound of 'horse' and 'snake'.SoulUrge Number: 6. Expression Number: 4. People with this name have a deep inner desire for a stable, loving family or community, and a need to work with others and to be appreciated.he name Roslyn is a German baby name. In German the meaning of the name Roslyn is: Compound of 'horse' and 'snake'. SoulUrge Number: 6. Expression Number: 4. People with this name have a deep inner desire for a stable, loving family or community, and a need to work with others and to be appreciated.