O

obesity (ō-BĒ-sĭt-ē):

Abnormal increase in the proportion of fat cells resulting in excess body weight for height.

obstetrician (ob-stĕ-TRISH-ăn):

The person who specializes in the study of obstetrics and gynecology and are referred to as OB/GYN Obstetrics and Gynecology.

Obstetrics (ŏb-STE-triks):

Medical specialty dealing with pregnancy, childbirth, and puerperium.

occipital lobe (ok-SIP-ĭt-ăl lōb):

Region of the cerebral cortex directly beneath the occipital bone of the cranium.

occlude (ŏ-KLOOD):

Block or close tightly.

oculomycosis (ŏk-ū-lō-mī-KŌ-sĭs):

Abnormal condition of the eye caused by a fungus.

olfaction (ŏl-FĂK-shŭn):

Special sense responsible for smell, which has a unique, direct connection to the cerebrum.

oligodendrocyte (ol-ĭ-gō-DEN-drŏ-sīt):

Glial cell type in the CNS that provides the myelin insulation for axons in tracts.

oligohydramnios (ŏl-ĭg-ō-hī-DRĂM-nē-ōs):

A condition where there is minimal amniotic fluid within the placental sac. Too little fluid can restrict the fetus from movement and growth.

oligomenorrhea (ŏl-ĭ-gō-mĕn-ō-RĒ-ă):

Infrequent or irregular periods.

oligoovulation (ol-i-gō-ov-yŭ-LĀ-shŏn):

Infrequent ovulation.

oligospermia (ŏl-ĭ-gō-SPĔR-mē-ă):

Condition of scanty sperm.

oliguria (ŏl-ĭg-Ū-rē-ă):

Scanty urine (output).

omentum (ō-MENT-ŭm):

Fatty tissue that stretches over the abdomen, plays a role in immune response and the growth of certain cancers.

omphalitis (ŏm-făl-Ī-tĭs):

Inflammation of the umbilicus.

omphalocele (ŏm-FĂL-ō-sēl):

Herniation of the umbilicus.

onychocryptosis (ŏn-ĭ-kō-krip-TŌ-sis):

Abnormal condition of a hidden nail.

onychomalacia (ŏn-ĭ-kō-mă-LĀ-shă):

Softening of the nails.

onychomycosis (on-i-kō-mī-KŌ-sĭs):

Abnormal condition of a fungus in the nails.

onychophagia (ŏn-ĭ-KŎF-ă-jē):

Eating the nails (nail biting).

oocyte (Ō-ŏ-sīt):

Female gamete.

oophorectomy (ō-ŏ-fŏ-REK-tŏ-mē):

Surgical removal of the fallopian/uterine tubes.

oophoritis (ō-ŏf-ō-RĪ-tĭs):

Inflammation of the ovary.

ophthalmalgia (ŏf-thăl-MĂL-jē-ă):

Pain in the eye.

ophthalmia neonatorum (of-THAL-mē-ă nē-ŏ-NĂ-tōr-ăm):

Conjunctivitis in newborns (severe).

ophthalmic (of-THAL-mik):

Pertaining to the eye.

ophthalmologist (ŏf-thăl-MŎL-ō-jĭst):

Specialist of the eye.

ophthalmology (Ophth) (ŏf-thăl-MŎL-ō-jē):

Study of the eye.

ophthalmopathy (ŏf-thăl-MŎP-ă-thē):

Disease of the eye.

ophthalmoplegia (of-thal-mō-PLĒ-j(ē-)ă):

Paralysis of the eye.

ophthalmoscope (of-THAL-mŏ-skōp):

Instrument used to view the eye.

ophthalmoscopy (of-thal-MOS-kŏ-pē):

Process of viewing the eye.

opsonization (ŏp-să-nĭ-ZĀ-shŭn):

An antibody or an antimicrobial protein binds to a pathogen, thereby marking it as a target for phagocytes.

optic (OP-tik):

Pertaining to vision.

Optician (ŏp-TĬSH-ăn):

Specialist who fills prescriptions for lenses but cannot prescribe.

Optometrist (ŏp-TŎM-ĕ-trĭst):

Specialist who diagnoses, treats and manages diseases and disorders of the eye (Doctor of Optometry).

optometry (op-TOM-ĕ-trē):

Measuring vision.

oral (ŌR-ăl):

Pertaining to the mouth.

orchialgia (or-kē-ĂL-jē-ă):

Pain in the testis.

orchiditis (or-kĭ-DĪ-tĭs):

Inflammation of the testis.

orchiectomy (or-kē-EK-tŏ-mē):

Excision of the testis.

orchiepididymitis (or-kē-ĕp-ĭ-dĭd-ĭ-MĪ-tĭs):

Inflammation of the tested and epididymis.

orchiopexy (or-kē-ō-PĔK-sē):

Surgical fixation of the testicle.

orchioplasty (OR-kē-ō-plăs-tē):

Surgical repair of the testis.

orchiotomy (or-kē-ŎT-ō-mē):

Incision into the testis.

orchitis (or-KĪ-tĭs):

Inflammation of the testis.

organ (OR-găn):

Anatomically distinct structure of the body composed of two or more tissue types.

organ system (OR-găn SIS-tĕm):

Group of organs that work together to perform major functions or meet the physiological needs of the body.

organelle (OR-gă-nel):

Tiny functioning units inside of a cell.

organism (OR-găn-ĭzm):

Living being that has a cellular structure and can independently perform all physiological functions necessary for life.

orgasm (OR-gazm):

A climax of sexual stimulation.

oropharynx (or-ō-FAR-ingks):

The oropharynx is a passageway for both air and food and borders the nasopharynx and the oral cavity.

orthopnea (or-THŎP-nē-ă):

Breathing is easier in a straight position.

osmosis (oz-MŌ-sĭs):

A process by which molecules of a solvent tend to pass through a membrane from a less concentrated solution into a more concentrated one.

ostectomy (ŏs-TĔK-tō-mē):

Excision of bone.

osteoarthritis (ä-stē-ō-är-ˈthrī-təs):

Inflammation of bone and joint.

osteoblast (OS-tē-ō-blast):

Developing bone cell.

osteochondritis (os-tē-ō-kon-DRĪT-ĭs):

Inflammation of bone and cartilage.

osteoclasis (ŏs-tē-ō-KLĀ-sis):

Surgical breaking of a bone.

osteocyte (OS-tē-ŏ-sīt):

Bone cell.

osteomalacia (os-tē-ō-mă-LĀ-sh-ē-ă):

Softening of the bones.

osteomyelitis (os-tē-ō-mī-ĕ-LĪT-ĭs):

Inflammation of bone and bone marrow.

osteonecrosis (os-tē-ō-nĕ-KRŌ-sĭs):

Abnormal condition of bone death (lack of blood supply).

osteopenia (os-tē-ō-PĒ-nē-ă):

Abnormal reduction of bone mass.

osteopetrosis (ŏs-tē-ō-pĕ-TRŌ-sĭs):

Abnormal condition of stone-like bones.

osteosarcoma (ŏs-tē-ō-săr-KŌ-mă):

Malignant tumor of bone.

otalgia (ō-TĂL-jē-ă):

Pain in the ear.

otologist (ō-TŎL-ō-jĭst):

Specialist who studies and treats disorders and diseases of the ear.

otology (ō-TŎL-ō-jē):

Study of the ear.

otomastoiditis (ō-tō-mas-toyd-ĪT-ĭs):

Inflammation of the ear and mastoid bone.

otomycosis (ō-tō-mī-KŌ-sĭs):

Abnormal condition of fungus in the ear.

otopyorrhea (ō-tō-pī-ō-RĒ-ă):

Discharge of pus from the ear.

otorhinolaryngologist (ō-tō-RĪ-nō-lăr-ĭn-GŎL-ō-jĭst):

Specialist or physician who studies and treats disease and disorder of the ears, nose and throat.

otorrhea (ō-tō-RĒ-ă):

Discharge from the ear.

otosclerosis (ō-tō-sklē-RŌ-sĭs):

Hardening of the ear.

otoscope (Ō-tō-skōp):

Instrument used to view the ear.

otoscopy (ō-TŎS-kō-pē):

Process of viewing the ear.

ovarian cancer (ō-VAR-ē-ăn KAN-sĕr):

Malignant tumor of the ovary.

ovaries (Ō-vă-rēs):

Two almond shaped organs (female gonads) located at the entrance to the fallopian tubes; responsible for storing of egg cells (ova) and production of estrogen and progesterone hormones.

ovulation (ov-yŭ-LĀ-shŏn):

Release of ovum from a mature graafian follicle.

ovum (ova) (Ō-vŭm):

Female egg cells.

oximeter (ok-SIM-ĕt-ĕr):

Instrument used to mesure oxygen.

oxytocia (ok-si-TŌ-sia):

A rapid birth.

Attribution

Except where otherwise noted, this book is adapted from Medical Terminology by Grimm et al. (2022), Nicolet College, CC BY 4.0 International. / A derivative of Building a Medical Terminology Foundation by Carter & Rutherford (2020), and Anatomy and Physiology by Betts, et al., CC BY 4.0, which can be accessed for free at OpenStax Anatomy and Physiology.