Having no head; beheaded; as, a headless body, neck, or carcass. [1913 Webster]
Destitute of a chief or leader. Sir W. Raleigh. [1913 Webster]
Destitute of understanding or prudence; foolish; rash; obstinate; mindless. [1913 Webster]
"Witless headiness in judging or headless hardiness in condemning." [1913 Webster]

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THESAURUS

headless

brainless, crownless, foolish, ignorant, inept, insensate, irrational, lackbrained, lean-minded, lean-witted, mindless, not bright, of little brain, pea-brained, pin-brained, reasonless, senseless, slackminded, slackwitted, topless, ungifted, unintellectual, unintelligent, unreasoning, untalented, unthinking, unwise, witless

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