1 a ghost.
2 a haunting presentiment or preoccupation (the spectre of war).
3 (in comb.) used in the names of some animals because of their thinness, transparency, etc. (spectre-bat; spectre-crab).
Phrases and idioms:
Spectre of the Brocken a huge shadowy image of the observer projected on mists about a mountain-top (observed on the Brocken in Germany).
Etymology: F spectre or L spectrum: see SPECTRUM
Useful english dictionary. 2012.