Short court or courtier
Kourtnie is a modern creative spelling of Courtney. It originates from an Old French surname, likely referring to someone who lived or worked at a royal court, or a nickname for someone with a 'short nose' (curt nez).
Less common today
Kourtnie isn't in the latest US Top 1000. It last peaked at #2,841 in 1990.
US births per 5-year period, 1990βpresent (SSA data).