Synonyms for Headless (same or very similar meaning)
WordNet sense 1 (not using intelligence):
brainless
WordNet sense 2 (lacking intelligence):
unintelligent
WordNet sense 3 (having had the head cut off):
beheaded
WordNet sense 4 (lacking a head or a clearly defined head):
acephalous
From the ODE community, based on WordNet
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