Google's Gmail Web-based email service runs on the Internet Message Access Protocol system, but it also offers Post Office Protocol mail server access.
Definition of LUMEN. 1. 2. : the bore of a tube (as of a hollow needle or catheter). 3. : a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of one candle intensity.
Answer Wiki. Quora User, Desperately in love with Bio.. Lumen simply means a âspaceâ or an âopeningâ. The space can be surrounded by walls on all sides like a blood vessel or it can be the cavity within a tubular organ such as food pipe and trachea or just a space inside a hollow organ such a intestine.