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Webster 1913 Edition

Periderm

Per′i-derm

,

Noun.

1.

(Bot.)

The outer layer of bark.

2.

(Zool.)

The hard outer covering of hydroids and other marine animals; the perisarc.

Definition 2024

periderm

periderm

English

Noun

periderm ‎(plural periderms)

(botany) The outer layer of plant tissue comprising of the phellem, phellogen and the phelloderm.
(zoology) The perisarc; the hard outer layer of hydroids and other marine animals.

References

periderm in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913