The Collaborative International Dictionary of English v.0.48:
Mesogloea \Mes`o*gl[oe]"a\, n. [NL., fr. Gr. me`sos middle + ? a glutinous substance.] (Zool.) A thin gelatinous tissue separating the ectoderm and endoderm in certain coelenterates. -- Mes`o*gl[oe]"al, a. [1913 Webster]