proostracum

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noun

The anterior prolongation of the guard of the phragmocone of belemnites and allied fossil cephalopods, whether horny or calcareous.

OriginAncient Greek προ- →
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Meanings

nounproostracum (plural proostraca)

plural proostraca

  1. biologyThe anterior prolongation of the guard of the phragmocone of belemnites and allied fossil cephalopods, whether horny or calcareous.

Origin

  1. Ancient Greekπρο-“before”
  2. Englishproostracum

From Ancient Greek προ- (pro-, “before”) + ὄστρᾰκον (óstrăkon, “shell”).

More words from Ancient Greek

Full word history & related roots →
Cite this entry
APA

proostracum. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/proostracum

MLA

“proostracum.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/proostracum. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “proostracum,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/proostracum.

Source: proostracum on Wiktionary, CC BY-SA 4.0.