noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   The middle layer of the gonophore in the Hydrozoa.
2. 2
   A membranous structure that encloses the developing eggs within the oviduct of a female arthropod.

Etymology

From meso- + theca.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.