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Webster 1913 Edition

Adj.

[

Poly-

+ Gr. [GREEK] a chamber.]

(Zool.)

Many-chambered; – applied to shells of Foraminifera and cephalopods. See Illust. of

polythalamous ‎(comparative more polythalamous, superlative most polythalamous)

(zoology) Having many chambers.
The shells of Foraminifera are polythalamous.