Without a head; decapitated.
How did the headless horseman see to chase Ichabod?
Without leadership.
The headless army blundered along after the death of their general, accomplishing nothing.
(of a phrase or compound) Not having a head morpheme or word.
Running without a graphical user interface; running without any attached output device (e.g., monitor) or input device (e.g., keyboard, mouse).
(of beer) Without a head of foam.
Heedless.