Ob-e-lisk, berna; bernod
Ob-jec-tion, gwrthddadl, gwrtheb
Ob-jec-tive, gwrthrychawl
Ob-la-tion, offrwm; rhodd
Ob-nox-ious, darostyngiedig, beius
Ob-serv-ance, parch; cadwad
Ob-so-lete, anarferedig, henaidd
Ob-sta-cle, rhwystr, attalfa
Ob-sti-nate, cildyn, cyndyn, gwrthnysig
Ob-struc-tion, rhwystr, lludd; tagfa