to·men·tum (t?-m?n?t?m)n. pl. to·men·ta (-t?) Biology A covering of dense matted hairs.[Latin t?mentum, cushion stuffing.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.tomentum (t??m?nt?m) n, pl -ta (-t?) 1. (Botany) a feltlike covering of downy hairs on leaves and other plant parts2. (Anatomy) a network of minute blood vessels occurring in the human brain between the pia mater and cerebral cortex[C17: New Latin, from Latin: stuffing for cushions; related to Latin tum?re to swell] tomentose, tomentous adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014to?men?tum (t??m?n t?m) n., pl. -ta (-t?). a dense covering of woolly or matted hairs, as on a leaf. [1690?1700;