Lacking a head or leader; headless, either literally (in biology) or figuratively (in organization or government).
From Greek 'a-' (without) + 'kephale' (head) + '-ous' (adjective suffix meaning having the quality of). This classical formation was adopted into English scientific and political vocabulary around the 17th century.
Acephalous is the fancy term for something that functions without a head—some fish species are technically acephalous by zoological definition, and it's how medieval historians describe certain revolutionary groups that somehow organized themselves anyway.
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