old-fashioned To remain vigilant or carefully watchful (for something or someone); to act as a guard or watch. In this phrase, "cave" derives from a Latin word meaning "beware." The gang employed youths from the area to keep cave and give a signal if any police officers arrived. I offered to keep cave at the door, as I had no intention of risking my life in that creepy old house.
keep caveact as lookout. school slang
Cave is a Latin word meaning ‘beware!’ Pronounced as one or two syllables, cave was the traditional warning uttered by a schoolchild to let others know that a teacher was approaching.