Small valley or valley of flax
A modern American coinage likely blending the English surname Dale, meaning valley, with the popular suffix -lyn. It may also be interpreted as a variation of the name Dallin, which refers to a valley where flax grows.
Less common today
Daelyn isn't in the latest US Top 1000. It last peaked at #2,083 in 2011.
US births per 5-year period, 1990βpresent (SSA data).