What does arachnoid mater literally mean?

Answer 1

The arachnoid mater is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is the middle layer between dura mater and pia mater. It is reticulous. Small vessels pass through it. Inflamation is called archnoiditis

Answer 2

"Arachnoid" means "like or belonging to a spider" (it is frequently incorrectly defined as "like a spider's web" because of this specific medical use of it.). "Mater" means "mother" in Latin. The reason for the "mater" part is that the Arabic anatomists identified the pia mater and dura mater, the two other parts of the meninges and called them respectively the "gentle mother of the brain" and the "thick mother of the brain". These somewhat fanciful terms were translated into Latin as "pia mater" ("gentle mother") and "dura mater" ("tough mother") in the middle ages. But the cobwebby middle layer was not identified as a separate thing until the 17th century, and its spiderweb-like appearance gave rise to the "arachnoid" term. But the other parts of the meninges had "mater" at the end of their names, so they tacked it on the end of this term as well. As a result, while the terms pia mater and dura mater make very little sense, the term arachnoid mater makes no sense whatsoever.