National Cancer Institute
U.S. National Institutes of Health | www.cancer.gov
In English | En español
NCI Home
Cancer Topics
Clinical Trials
Cancer Statistics
Research & Funding
News
About NCI
Dictionary of Cancer Terms
In English   En español
Page Options
Print This Page
Quick Links
Director's Corner
Updates from the Director

Dictionary of Cancer Terms
Cancer-related terms

NCI Drug Dictionary
Definitions, names, and links

Funding Opportunities
Research and training

NCI Publications
Order/download free booklets

Advisory Boards and Groups
Information, meetings, reports

Science Serving People
Learn more about NCI

Español
Información en español
Quit Smoking Today
NCI Highlights
Report to Nation Finds Declines in Cancer Incidence, Death Rates

High Dose Chemotherapy Prolongs Survival for Leukemia

Prostate Cancer Study Shows No Benefit for Selenium, Vitamin E

The Nation's Investment in Cancer Research FY 2009

Past Highlights
Search for
# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
In English   En español

pupil (PYOO-pil)

 The round opening in the center of the iris (the colored tissue that makes the "eye color" at the front of the eye). The pupil changes size to let light into the eye. It gets smaller in bright light and larger as the amount of light decreases.

Enlarge
Eye anatomy; two-panel drawing shows the outside and inside of the eye. The top panel shows outside of the eye including the eyelid, pupil, sclera, and iris; the bottom panel shows inside of the eye including the cornea, lens, ciliary body, retina, choroid, optic nerve, and vitreous humor.




Previous Definitions:pulmonary sulcus tumor, pulmonologist, Pulmozyme, pump, punch biopsy
Next Definitions:Purinethol, purple clover, purple coneflower, PUVA therapy, PV701

A Service of the National Cancer Institute
Department of Health and Human Services National Institutes of Health USA.gov