What is the literal meaning of the scientific name for the cactus wren?
According to the Helm Dictionary of Scientific Bird Names:


Kampylos, καμπúλος (Greek): curved, bent;
Rhynchos, ῥύγχος (Greek): bill.


Also, for the specific epithet:


Brunneus (late Latin): brown;
Capillus (Latin): hair.


Page with the Genus name: https://books.google.com.au/books?id=-RfSBAAAQBAJ&amp;lpg=PP1&amp;pg=PA87#v=onepage&amp;q&amp;f=false

Page with the specific epithet: https://books.google.com.au/books?id=-RfSBAAAQBAJ&amp;lpg=PP1&amp;pg=PA78#v=onepage&amp;q&amp;f=false