Kaylee is a modern American name invention and therefore has no etymology or specific meaning. The name was merely created by putting together appealing sounds: in this case, the popular “Kay” prefix with the popular “Lee” suffix. Kaylee’s popularity has more to do with the “K” kraze: Kaitlin, Kayden, Kayla, Kaylyn, Kylee, Kyla, Keely. It’s difficult to differentiate them, especially since many of them are modern inventions and haven’t been around long enough to prove their staying-power. The closest distant relatives we can find for some of these name creations are Irish: Caoilainn (pronounced KAY-lin) means “fair and slender” and Cadhla (pronounced KEE-la or KIE-la) implies a woman so beautiful that only poets can describe her. Kaylee, however, is pronounced differently and therefore cannot really be considered an anglicized version of these other Irish names. Kaylee is simply a sweetly modern American baby girl’s name that follows the trend of cutesy casual “-ee” names (Ashlee, Haylee, Rilee, etc.). Such names are really only used in America and sometimes Canada. They aren’t as common in other English-speaking countries.
Kaylee first appeared on America’s Top 1000 list in 1984, but it quickly made significant jumps in a short time span, rising to the Top 100 by 1998. Not content to stop there, Kaylee got as high as #26 on the charts (2009). Today she seems to be parking herself comfortably on America’s Top 50. Right now Kaylee is the preferred spelling of this oft-respelled name (more than half are given the Kaylee spelling). Kayleigh is second most popular. If there’s one thing we can say about American parents, they like to invent new names and they’re not shy about whacky spelling dissimilarities.