Dictionary

ovary, dermoid cyst of the See ovarian teratoma.

ovary cyst, follicular See cyst of the ovary, follicular.

overgrowth Excessive growth. Also sometimes called gigantism.

overgrowth syndrome A condition with multiple features, most notably excessive growth. A number of overgrowth syndromes affect children, such as fragile X syndrome. Excessive growth of specific body parts is also a feature of a number of disorders, such as Beckwith-Wiedemann syndrome, in which there is macroglossia (a large tongue due to overgrowth of the…

overload, iron See excess iron.

over-the-counter drug A drug that is available without a prescription, in contrast to prescription drugs that require a physician’s order. Abbreviated OTC.

overweight Weighing more than is healthy for a particular body type and build. Overweight is often defined as having a body mass index (BMI) from 25 up to 30. See also body mass index; obese.

ovulation The release of the ripe egg (ovum) from the ovary. The egg is released when the cavity surrounding it (the follicle) breaks open in response to a hormonal signal. Ovulation occurs around 14 or 15 days from the first day of the woman’s last menstrual cycle. When ovulation occurs, the ovum moves into the…

ovum An egg within the ovary of the female. An ovum can combine with sperm to form a zygote.

oximetry The process of determining the level of oxygenation in arterial blood, an important measure of whether the heart and lungs are working properly. Oximetry may be done continuously during certain medical treatments or surgery, or it may be done sporadically to monitor a patient’s health.

oximetry catheter See catheter, oximetry.

oxygen The odorless gas that is present in the air and necessary to maintain life. Oxygen may be given in a medical setting, either to reduce the volume of other gases in the blood or as a vehicle for delivering anesthetics in gas form. It can be delivered via nasal tubes, an oxygen mask, or…