Modern blend of Mace and Lynn
Macelyn is a modern American invention, likely created by combining the surname-turned-first-name Mace with the popular suffix -lyn. While Mace can trace back to the Old French word for a weapon or a spice, in this context it serves as a contemporary stylistic choice. The addition of -lyn adds a feminine touch, following the pattern of names like Gracelyn or Raelyn.
Less common today
Macelyn isn't in the latest US Top 1000. It last peaked at #11,778 in 2014.
US births per 5-year period, 1990βpresent (SSA data).