D defs.my
Entry 2 senses Webster, 1913

Theca

· The·ca · IPA /ˈθiːkə/
01 n. A sheath; a case; as, the theca, or cell, of an anther; the theca, or spore case, of a fungus; the theca of the spinal cord.
pl. Thecae ((#))
  1. 1.
    A sheath; a case; as, the theca, or cell, of an anther; the theca, or spore case, of a fungus; the theca of the spinal cord.
  2. 2.
    The chitinous cup which protects the hydranths of certain hydroids.(Zool.)