Slender or narrow
Keylen is likely a modern American variation of the Gaelic name Caelan or the English Kellen. It shares the etymological root meaning 'slender' or 'narrow,' often used to describe a physical trait or a narrow strip of land. As a contemporary invention, it follows the popular trend of using the '-len' suffix for unisex appeal.
Less common today
Keylen isn't in the latest US Top 1000. It last peaked at #4,499 in 2006.
US births per 5-year period, 1990βpresent (SSA data).