over and under
odalisque
Otto comes to mind.
oriole
orlop
Obediah?!
osier
Orc, Olog-hai
Old Navy and OshKosh B'Gosh are clothing brands. They begin with the letter O.
A few examples of 3-letter words starting with the letter O are:owloweoaroatown
Some six letter words starting with O are:objectoblongoccultocelotoddityoffendofficeorangeorioleorphanoverdooxygen
insects starting with letters O X and Z
Otago is a region in South Island, New Zealand. It begins with the letter O.