onrushing

oohing

oompahing

oozing

opacifying

opalescing

opaquing

opening

operagoing

operating

opiating

oping

opining

oppilating

opposing

oppressing

oppugning

opsonifying

opsonising

opsonizing

optimising

optimizing

opting

optioning

orating

orbing

orbiting

orchestrating

ordaining

ordering

organising

organizing

orgasming

orientalizing

orientating

orienteering

orienting

originating

ornamenting

orphaning

orthogonalizing

oscillating

osculating

osmosing

ossifying

ostracising

ostracizing

othering

ouching

oughting