The meaning of the name Callen is Slender, Thin. The origin of the name Callen is Irish. This is the culture in which the name originated, or in the case of a word, the language.
From the Gaelic name CAOLĂN.
Callen is on 182 BN name lists Callen is currently not ranked on the BN charts Callen is currently #570 in U.S. births
Callen 
