Combination of Brittany and the suffix -lyn
Brittlyn is a modern American invention, likely created by blending the geographic name Brittany (referring to the region in France) with the popular melodic suffix -lyn. While Brittany originally means 'from Britain,' this compound form is chosen primarily for its contemporary sound rather than its etymological roots.
Less common today
Brittlyn isn't in the latest US Top 1000. It last peaked at #10,627 in 2001.
US births per 5-year period, 1990βpresent (SSA data).