The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
as-
DEFINITION:
To burn, glow. Oldest form *2es-, colored to *2as-. Derivatives include arson and azalea. 1. Extended form *asg-.ash1, from Old English æsce,asce, ash, from Germanic *askn-.2. Suffixed form *s--.Ara, from Latin ra, altar, hearth. 3. Suffixed (stative) form *s--.a.arid, from Latin ridus, dry, parched, from rre, to be dry; b.ardent, ardor, arson, from Latin rdre, to burn, be on fire, from ridus, parched. 4. Extended form *asd-.a.zamia, from Greek azein, to dry; b.azalea, from Greek azaleos, dry. (Pokorny s- 68.)
2es-, colored to *
n-. 2. Suffixed form *
s-
-. a. arid, from Latin 
s- 68.) 
