or dip·lo·ë D0239800 (dĭp′lō-ē′)n. The spongy, porous, bony tissue between the hard outer and inner bone layers of the cranium.[Greek diploē, a fold, doubling, from feminine of diploos, twofold; see dwo- in Indo-European roots.]dip′lo·ic(-lō-ĭk) adj.