Courtly, polite, or from the short pool
Kortlyn is a modern American invention, likely created by blending the surname-turned-first-name Courtney with the popular suffix -lyn. It may also be interpreted as a variant of Cortland, an English place name meaning 'land of the short pool'.
Less common today
Kortlyn isn't in the latest US Top 1000. It last peaked at #7,909 in 2014.
US births per 5-year period, 1990βpresent (SSA data).