Soldier or merciful
Myleigh is a modern American creative spelling of Miley. It likely derives from the name Miles, which has roots in the Latin word for soldier or the Slavic element for gracious and merciful.
Less common today
Myleigh isn't in the latest US Top 1000. It last peaked at #1,527 in 2008.
US births per 5-year period, 1990βpresent (SSA data).