Slender or girl
Caileen is a modern phonetic anglicization of the Irish word 'cailín', which simply means 'girl'. It is often associated with the name Caoilinn, which combines the elements for 'slender' and 'fair'.
Less common today
Caileen isn't in the latest US Top 1000. It last peaked at #8,628 in 1992.
US births per 5-year period, 1990–present (SSA data).
