organ system ; organ / sy.together+stem.stand
origin ; ori.rise+gin
oris ; os ; or.mouth+is
oropharynx ; or.mouth+o+pharynx.throat
orthopnea ; orth.straight+o+pn.blow.breathe+ea.n
orthovoltage machines ; ortho.straight+volt+age.n / machine+s
ossiculectomy ; ossi.bone+cul.small+( ec.out+tom.cut+y.n)
ostealgia ; oste.bone+alg.pain+ia.n
ostectomy ; ost.bone+( ec.out+tom.cut+y.n)
osteitis ; oste.bone+itis.inflammation
osteitis deformans ; oste.bone+itis.inflammation / ( de.breaking+form.form+ans)
osteoarthritis ; OA ; oste.bone+o+arthr.joint+itis.inflammation
osteoblast ; oste.bone+o+blast.germ
osteoclasis ; oste.bone+o+clas.break+is.n
osteoclast ; oste.bone+o+clast.break
osteocyte ; oste.bone+o+cyte.cell
osteocyte lacuna ; oste.bone+o+cyte.cell / lacuna.pit
osteocyte process ; oste.bone+o+cyte.cell / ( pro.forth+cess.go)
osteoma ; oste.bone+oma.tumor
osteomalacia ; oste.bone+o+malac.soft+ia.
osteomyelitis ; oste.bone+o+myel.marrow+itis.inflammation
osteopathy ; oste.bone+o+path.feel.suffer.disease+y.n
osteoporosis ; oste.bone+o+por.perforation+osis.abnormalstate
osteorrhagia ; oste.bone+o+rrhag.burst+ia.n
osteosarcoma ; oste.bone+o+sarc.flesh+oma.tumor
otalgia ; ot.ear+alg.pain+ia.n
otitis externa ; ot.ear+itis.inflammation / ex.out+ter+na
otitis media ; OM ; ot.ear+itis.inflammation / med.middle+ia
otomycosis ; ot.ear+o+myc.fungus+osis.abnormalstate
otoplasty ; ot.ear+o+plast.form+y.n
otorhinolaryngology ; ORL ; ot.ear+o+rhin.nose+o+laryng.larynx+o+log.science+y.n
otorrhea ; ot.ear+o+rrhe.flow+a.n
otoscopy ; ot.ear+o+scop.observe+y.n
outer root sheath ; out.outside++er.more / root / sheath.covering
oval fossa ; ov.egg+al.a / fossa.ditch
oval window ; ov.egg+al.a / window
ovarian cyst ; ( ov.egg+ari)ovary+an.a / cyst.pouch.sac
ovarian pregnancy ; ( ov.egg+ari)ovary+an.a / pre.before+gn.gen.birth+ancy.n
ovarian tumor ; ( ov.egg+ari)ovary+an.a / ( tum.swell+or.n)
ovary ; ov.egg+ary
ovulation ; ov.ovum.egg+ul+at+ion.n
ovum ; ov.egg+um.n
oxygen ; O2 ; oxy.sharp+gen.birth
oxytocin ; oxy+toc.tikt.childbirth+in.hormone