Definition of theca in English:



  • 1A receptacle, sheath, or cell enclosing an organ, part, or structure, in particular.

    1. 1.1Anatomy The loose sheath enclosing the spinal cord.
      • ‘The vertebral foramen houses the theca and spinal nerves.’
      • ‘The theca contains the cauda equina or nerve roots.’
    2. 1.2Zoology A cuplike or tubular structure containing a coral polyp.
      • ‘Despite its good preservation, this single specimen did not show all aspects of the theca.’
      • ‘In the ‘echinoderm’ reconstruction, the theca lies with the convex side upwards and the appendage is interpreted as an anterior feeding arm.’
      • ‘The theca around the column is smooth, sometimes with weak longitudinal muscles.’
      • ‘It is notable that both specimens also display asymmetry in the overall structure of their thecae.’
      • ‘Calices and thecae are commonly intact, but typically lack feeding appendages.’
    3. 1.3Botany Either of the lobes of an anther, each containing two pollen sacs.
      • ‘At this stage, at least one theca is already opened, and pollinators are attracted to the flowers.’
      • ‘Stamens are didynamous, but the yellow anthers occur close together, with their divergent thecae spreading to the outside.’
      • ‘As pollinators removed pollen from the thecae, their walls collapsed and the anthers curled down gradually.’
      • ‘Each sequence of thecae forms a stipe, or branch, and colonies varied in the numbers of stipes that they possessed.’
      • ‘The percentage of thecae that dehisced longitudinally varied greatly among rice varieties.’
      bag, pouch, bladder, blister
      View synonyms
    4. 1.4Anatomy The outer layer of cells of a Graafian follicle.
      • ‘The term ‘follicle complex’ has been proposed to include the follicle, basement membrane, and the theca, including its blood vessels.’
      • ‘The follicle is surrounded by a theca, derived from the stromal compartment of the ovary and is always separated from this compartment, throughout development and final oocyte maturation, by a basement membrane.’


Early 17th century: via Latin from Greek thēkē case.