Heather field
Hadlei is a modern spelling variation of the English surname Hadley. It refers to a field or meadow covered in heather, a hardy flowering shrub common in the British Isles. This specific spelling adds a contemporary, stylized flair to a traditional nature-inspired name.
Less common today
Hadlei isn't in the latest US Top 1000. It last peaked at #9,529 in 2013.
US births per 5-year period, 1990βpresent (SSA data).