Here are some common medical first words: 

• Acr- (G) pertaining to extremity: acrodermatitis, a dermatitis of the limbs.
• Aden- (G) pertaining to a gland: adenitis, inflammation of a gland.
• Bio- (G) pertaining to life: biopsy, inspection of living organism (or tissue).
• Bleph- (G) pertaining to eyelids: bleph-
• aritis, inflammation of an eyelid.
• Cardi- (G) pertaining to heart: cardialgia, pain in the heart.
• Cephal- (G) pertaining to head: cephalalgia, headache.
• Cheil- (G) pertaining to lip: cheilitis, inflammation of the lip.
• Cheir- (G) pertaining to hand: cheirospasm, writer's cramp.
• Chole- (G) pertaining to bile: cholecyst, the gallbladder.
• Chondr- (G) pertaining to cartilage: chondrectomy, removal of a cartilage.
• Cleid- (G) pertaining to clavicle: cleidocostal, pertaining to clavicle and ribs.
• Colp- (G) pertaining to vagina: colporrhagia, vaginal hemorrhage.
• Cost- (G) pertaining to rib: costalgia, pain in the ribs.
• Crani- (L) pertaining to skull: craniotomy, surgical opening in skull.
• Crypt- (G) pertaining to anything hidden: cryptogenic, of hidden or unknown origin.
• Cyst- (G) pertaining to any fluid-containing sac: cystitis, inflammation of the bladder.
• Cyt- (G) pertaining to a cell: cystometer, a device for counting and measuring cells.
• Daery- (G) pertaining to lachrymal glands: dacryocyst, tear-sac.
• Derm- or dermat- (G) pertaining to skin: dermatoid, skinlike.
• Encephal- (G) pertaining to brain: encephalitis, inflammation of brain.
• Enter- (G) pertaining to intestine: enteroptosis, falling of intestine.
• Galaet- (G) pertaining to milk: galactose, a milk-sugar.
• Gastr- (G) pertaining to stomach: gastrectomy, excision of the stomach.
• Gynec- (G) pertaining to woman: gynecology, science of diseases pertaining to women.
• Hem- or hemat- (G) pertaining to the blood: hemopoiesis, forming blood.
• Hyster- (G) pertaining to uterus: hysterectomy, excision of uterus.