| Word Part | Definition | 
| µg | microgram | 
| g | gram | 
| gait | Manner or style of walking. | 
| galact/o | milk | 
| galactorrhea | Inappropriate lactation. | 
| galactose | One of the two simple sugars in the protein, lactose, found in milk. The other sugar is glucose. | 
| gallbladder | A reservoir for bile located under the right lobe of the liver. | 
| gallop | A third heart sound that resembles the sound of a galloping horse. | 
| gallstone | A hard mass that precipitates in the biliary tract, usually in the gallbladder. | 
| gam- | marriage, sexual union | 
| gamete | A mature sex cell. | 
| ganglion | A structure containing an aggregation of nerve cell bodies located in the peripheral nervous system. | 
| ganglion cyst | Swelling or tumor on a joint or tendon sheath due to trauma. | 
| ganglion/o | ganglion | 
| ganglioneuroma | A benign neoplasm that usually arises from the sympathetic trunk in the mediastinum. | 
| gangrene | Death and putrefaction of tissue usually due to a loss of blood supply. | 
| garg | gargle | 
| gastr/o | stomach | 
| gastralgia | Pain in the stomach or abdomen | 
| gastrectomy | Excision of part or all of the stomach. | 
| gastric | Pertaining to the stomach. | 
| gastric absorption | Uptake of substances via the stomach. | 
| gastritis | The painful inflammation of the stomach's lining. | 
| gastroenteritis | Inflammation of the gastrointestinal tract. | 
| gastroenterology | A subspecialty of medicine concerned with diseases of the digestive system and related structures including the esophagus, liver, gallbladder, and pancreas. | 
| gastrointestinal tract | Generally refers to the digestive structures stretching from the mouth to anus, but does not include the accessory glandular organs (liver; biliary tract; pancreas). | 
| gastroparesis | Chronic delayed gastric emptying. | 
| gastrostomy | Creation of an artificial external opening into the stomach for nutritional support or gastrointestinal compression. | 
| gavage | Forced feeding a patient especially through a tube passed into the stomach | 
| GB | gallbladder | 
| GC | gonorrhea | 
| GDM | gestational diabetes mellitus | 
| ge/o | soil | 
| gel/o | to freeze, congeal | 
| gemell/o | twins | 
| gemin- | double, twin | 
| -gen | producing, origin | 
| gen/o | to become, being born, producing | 
| gene | A unit of inheritance carrying a single trait occupying a certain location on a chromosome. | 
| -genesis | formation, development | 
| genetic | Pertaining to reproduction or to birth or origin. | 
| geni/o | chin | 
| -genic | producing, origin | 
| genit/o | reproduction | 
| genitalia | The male and female reproductive organs. | 
| genocide | The deliberate annihilation of a national, ethnic, or religious group. | 
| genome | The complete set of genes in the chromosomes of each cell. The human genome contains an estimated 30,000 to 40,000 genes. | 
| genomics | The systematic study of the complete DNA sequences (genome) of organisms. | 
| genotype | The genetic constitution of the individual. | 
| genu | Knee. | 
| genu varum | An outward slant of the thigh in which the knees are wide apart and the ankles close together. | 
| ger/o | old age | 
| GERD | gastroesophageal reflux disease | 
| geriatrics | The branch of health care concerned with aging and diseases of the elderly. | 
| germ | Any microorganism, particularly one that causes disease. | 
| germination | The early stages of the growth of seeds. The embryonic shoot and embryonic plant roots emerge. | 
| germinoma | A neoplasm of the germinal tissue of gonads, mediastinum, or pineal region. | 
| gest/o | to bear | 
| gestalt | A physical, mental or symbolic configuration where whole differs from, or is greater than, the sum of its parts. | 
| gestation | The time period of development from fertilization to birth. | 
| gesture | A movement that helps express a feeling, idea, intention or opinion. | 
| GFR | glomerular filtration rate | 
| GH | growth hormone | 
| GI | gastrointestinal | 
| giardiasis | An intestinal infection caused by the protozoan Giardia lamblia. It is spread via contaminated food and water and by direct person-to-person contact. | 
| giga- | billion | 
| gigant/o | huge | 
| gigantism | Abnormal growth due to an excess of growth hormone during childhood. | 
| gingiv/o | gums | 
| gingiva | Oral tissue surrounding and attached to teeth. Gum. | 
| gingivitis | Inflammation of gum tissue. | 
| glabella | The area between the eyebrows immediately above the nose. | 
| glanders | A chronic bacterial infection of horses occasionally transmitted to humans. | 
| glandular fever | Infectious mononucleosis. | 
| glare | A bright, dazzling light which produces discomfort and impairs vision. | 
| glasgow coma scale | A scale for measuring level of consciousness, especially after craniocerebral injury | 
| glaucoma | A disease that damages the optic nerve. Often caused by abnormally high pressure in the eye. | 
| gleason score | A method of classifying malignancy of prostate cancers. | 
| glenoid cavity | A depression in the lateral angle of the scapula that articulates with the head of the humerus. | 
| gli/o | glue-like | 
| -globin | containing protein | 
| globulin | Any of a class of proteins that are found in blood plasma, milk and muscle that are insoluble in pure water but soluble in dilute salt solutions | 
| globus | A sphere. A spherical structure. | 
| glomerul/o | glomerulus | 
| glomerulus | A small tuft of blood capillaries in the kidney that is an integral part of the nephron, the basic unit of the kidney. | 
| gloss/o | tongue | 
| glossitis | Inflammation of the tongue. | 
| glottis | The vocal apparatus of the larynx, situated in the middle section of the larynx. | 
| glucagon | A peptide hormone produced in the pancreas that opposes insulin. | 
| gluco- | relating to glucose | 
| glucose | Sugar in the blood that supplies energy to cells. | 
| glyc/o | glucose, sugar | 
| glycemic index | A numerical system of measuring the rate of blood glucose generation from a particular food item. | 
| glycemic load | A quantitative value of a measured amount of a specific food that is equal to the glycemic index of that food multiplied by the carbohydrate content of that food. | 
| glycine | A non-essential amino acid that is a major component of gelatin and silk fibroin. It used therapeutically as a nutrient. | 
| glycosuria | The appearance of an abnormally amount of glucose in the urine. | 
| gm | gram | 
| gnath- | jaw, cheek | 
| gnos/o | knowledge | 
| GnRH | gonadotropin-releasing hormone | 
| goiter | Enlargement of the thyroid gland causing a swelling in the front part of the neck. | 
| gon- | seed, genital | 
| gonad/o | sex glands | 
| gonadal | Pertaining to or arising from a gonad. | 
| gonads | The sex glands, ovary or testis. | 
| goni/o | angle | 
| gonorrhea | A sexually transmitted bacterial disease, mostly seen in young adults. | 
| gout | Acute arthritis that causes severe pain and swelling in the joints due to the accumulation of urate crystals. | 
| GP | general practitioner | 
| gr | grain | 
| -grade | step, degree in a scale | 
| graft | Any tissue or organ for transplantation. | 
| -gram | recording, metric unit of weight | 
| gram stain | A method of staining bacteria, which is important in their identification. | 
| granul/o | small grain | 
| granulation tissue | A vascular connective tissue formed on the surface of a healing wound, ulcer, or inflamed tissue. It consists of new capillaries and an infiltrate containing lymphoid cells, macrophages, and plasma cells. | 
| granuloma | A clump of cells that forms when the immune system fights harmful substance but cannot remove it from the body.  Often foreign bodies stimulate these cells. | 
| -graph | instrument that records | 
| -graphy | process of recording | 
| grav | gravida | 
| Graves disease | An immune disease that causes hyperthyroidism. | 
| gravid/o | pregnancy | 
| -gravida | pregnant | 
| gravidity | Pregnant. | 
| groin | The external junctural region between the lower part of the abdomen and the thigh. | 
| GSW | gunshot wound | 
| GTT | glucose tolerance test | 
| GU | genitourinary | 
| guaifenesin | An expectorant that also has some muscle relaxing action. It is used in many cough preparations. | 
| Guillain-Barre syndrome | A disorder in which the immune system attacks the nerves. A rare disease, usually preceded by a viral infection | 
| gutta | One drop. | 
| GVHD | graft-versus-host disease | 
| GXT | graded exercise test | 
| GYN | gynecology | 
| gynec/o | woman, female | 
| gynecology | The branch of medicine dealing with diseases unique to women, especially those of the genital tract and breasts. | 
| gynecomastia | Non-cancerous swelling of the breast tissue in males due to an imbalance of hormones.  Common in pre-adolescence, benign and self-limiting. | 
| gyno- | woman | 
| gyr- | ring, circle |