/tuy loh"sis/ , n. , pl. tyloses /-seez/ . Bot.
a bubblelike formation in the cavity of tracheids or vessels in the wood of trees, consisting of protoplasm intruded from adjacent parenchyma cells.
[ 1875-80; týlosis act of making callous, equiv. to tylo-, var. s. of tyloûn to make callous, hard, deriv. of týlos callus, lump, knob + -sis -SIS ]