means A ghost or phantom — or, figuratively, a haunting threat or dread that looms over the mind.

from From Latin 'spectrum,' meaning an appearance or apparition, built on 'specere,' to look or behold — the same root that peers out of 'spectacle,' 'inspect,' and 'spectator.' It drifted into English through French 'spectre' in the 1600s. Fittingly, the word for the thing you cannot help but stare at comes from the verb for staring itself.