What does the word 'holy-rood' mean?

The Rood Screen is a feature found in some very old churches, and probably the 'altar rail' that you see in most Catholic Churches is a remnant of it. It is a structure that separates the altar from the congregation as a symbol of the separateness and holiness of God.
'Holyrood' is the anglicized form of the Scottish phrase for ' holy cross' - haly ruid.