Further perusal of the AHD's etymology shows the Latin comes from the Greek khalan (in their transliteration), which in Latin would be transliterated as chalare, and hey presto:

http://makeashorterlink.com/?H2FE31E84

Latin chalo: to slacken, let down. No doubt emanuela can tell us when chalo would have mutated to become the form she is familiar with.

Bingley

Bingley