We're working on a new site. Click here to get a sneak preview.
Medical Dictionary


noun lu·men \ˈlü-mən\
plural lu·mi·na \-mə-nə\ or lumens

Medical Definition of LUMEN

:  the cavity of a tubular organ or part <the lumen of a blood vessel>
:  the bore of a tube (as of a hollow needle or catheter)
:  a unit of luminous flux equal to the light emitted in a steradian by a uniform point source of one candle intensity


How to use a word that (literally) drives some people nuts.
Test your vocab with our fun, fast game
Ailurophobia, and 9 other unusual fears