Of or pertaining to organisms lacking a head; without a cephalic region or head.
From Greek a- (without) and kephale (head), plus -ine (adjective-forming suffix). Scientific term appearing in 19th-century natural history texts.
While acephaline technically means the same thing as acephalous, scientists preferred this Latinate form in formal taxonomic descriptions—another case of English burying simple concepts in technical jargon!
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