hypotheca

noun plural -cae (-siː)

the inner and younger layer of the cell wall of a diatomCompare epitheca

Word Origin for hypotheca

from hypo- + theca
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012