Hadlee is a modern respelling of Hadley, an English surname and place name from the Old English words for "heather" and "clearing", so it is usually read as "heather meadow". The -lee ending puts it in the same family as Everlee and Kinslee, spellings American parents began to favor in the 2010s. Hadlee entered the US top 1000 in 2013, peaked at number 719 in 2016 and stands at number 931 among girls' names in 2025.