1. A doorway, entrance, or gate, especially one that is large and imposing.
2. An entrance or a means of entrance: the local library, a portal of knowledge.
3. The portal vein.
4. A website considered as an entry point to other websites, often by being or providing access to a search engine.

1. Of or relating to the portal vein or the portal system.
2. Of or relating to a point of entrance to an organ, especially the transverse fissure of the liver, through which the blood vessels enter.

[Middle English, from Old French, from Medieval Latin portāle, city gate, from neuter of portālis, of a gate, from Latin porta, gate. N., sense 3 and adj., from New Latin porta (hepatis), transverse fissure (of the liver), literally gate of the liver, perhaps ultimately translation of Akkadian bāb (ekalli), gate (of the palace), umbilical fissure of the liver (next to the transverse fissure).]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.