The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
awo-
DEFINITION:
An adult male relative other than one's father. 1.atavism, from Latin avus, grandfather. 2.avuncular, uncle, from Latin avunculus, maternal uncle. 3.ayah, from Latin avia, grandmother. (Pokorny ao-s 89.)
o-s 89.) 
