The state or quality of being headless; the condition of lacking a head, leadership, or common sense.
From 'headless' (without a head or without leadership) plus the noun suffix '-ness.' This abstract noun appeared in English by the 1600s.
The phrase 'running around like a chicken with its head cut off' describes headlessness perfectly—and weirdly, that actually happens: chickens can survive for 18 seconds without a head due to nervous system reflexes.
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