from The American Heritage® Dictionary of the English Language, 4th Edition
- adv. From the beginning.
from The Century Dictionary and Cyclopedia
- Literally, from the egg; hence, from the very beginning, generally with allusion to the Roman custom of beginning a meal with eggs.
Latin ab ōvō : ab, from + ōvō, ablative of ōvum, egg.(American Heritage® Dictionary of the English Language, Fourth Edition)
Borrowing from Latin ab ovo (literally "from the egg") (Wiktionary)