Gain a better understanding of medical terminology by searching our dictionary of more than 1,300 terms.


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All terms that start with the letter S
  • sickle cell trait

    Inheriting the gene for sickle cell anemia from only one parent. It causes no symptoms.

  • sigmoid


  • sinew

    A tendon or fibrous cord.

  • sinus

    A cavity in a bone or other tissue. Commonly used to describe the cavities in the skull that open into…

  • sinusitis

    Inflammation and infection of the sinuses.

  • sitz bath

    A bath in which only the hips and buttocks are immersed in water for relief of rectal or vaginal…

  • skeleton

    The hard bony framework of the human body that supports the tissues and protects the organs.

  • skull

    The bony framework of the head.

  • smallpox

    A viral disease that was once highly contagious. Characterized by high fever, vomiting, and blisters and sores on the skin…

  • smooth muscle

    A type of muscle tissue controlled by the involuntary nervous system, occurring in the walls of the uterus, intestines or…

  • sneeze

    To exhale breath from the nose and mouth in a sudden, involuntary action as a result of irritation of the…

  • Snellen's chart

    A chart of block letters used to test distant vision.

  • snoring

    Harsh breathing sounds during sleep caused by the vibration of the soft palate during inhalation.

  • soft palate

    The soft part of the roof of the mouth in the back, toward the throat.

  • soft tissue

    The substance of an organic body or organ consisting of cells and intercellular materials. The muscles and other nonbony tissues…

  • solar plexus

    The network of nerves in the center of the abdomen.

  • spasm

    A sudden, involuntary contraction of a muscle or group of muscles.

  • specimen

    A sample taken to study the nature of the whole.

  • speculum

    An instrument for opening a body cavity to permit visual inspection.

  • sperm

    The male germ cell. Also called spermatozoon.

  • sphincter

    A ring-shaped muscle that surrounds a natural opening in the body and can open or close it by relaxing or…