theca
Pronunciation: /ˈθiːkə/
noun ( plural thecae /-siː/)
- a receptacle, sheath, or cell enclosing an organ, part, or structure, in particular:
- Anatomy the loose sheath enclosing the spinal cord.
- Zoology a cup-like or tubular structure containing a coral polyp.
- Botany either of the lobes of an anther, each containing two pollen sacs.
- (also theca folliculi /fəˈlɪkjʊlʌɪ/) Anatomy the outer layer of cells of a Graafian follicle.

Origin:
early 17th century: via Latin from Greek thēkē 'case'