objetar - to object

obliterar - to obliterate, to erase

obrar - to build, to work

obsequiar - to give a gift

observar - to observe

obsesionar - to obsess, to haunt

obstinar - to insist

obturar - to block

ocasionar - to cause, to bring, to out

ocupar - to take up, to concern, to take care

ocultar - to hide