• (a.) Having four loculaments, or thecae.
Tet`ra·the'cal adjective [ Tetra- + thecal .] (Botany) Having four loculaments, or thecæ. 
tetrathecal Having four loculaments (cell of a pericarp in which the seed is lodged), or thecae: a case, covering, or sheath; such as, the pollen sac of an anther, the spore case of a moss, or the outer covering of the pupa of certain insects.