The·ca n.; pl. Thecae
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. Zool. (a) The chitinous cup which protects the hydranths of certain hydroids. (b) The more or less cuplike calicle of a coral. (c) The wall forming a calicle of a coral.
n 1: a case or sheath especially a pollen sac or moss capsule
2: outer sheath of the pupa of certain insects
[also: thecae (pl)]