The Collaborative International Dictionary of English v.0.48:
Synangium \Syn*an"gi*um\, n.; pl. Synangia. [NL., fr. Gr. ? + ? a hollow vessel.] (Anat.) The divided part beyond the pylangium in the aortic trunk of the amphibian heart. -- Syn*an"gi*al, a. [1913 Webster]