Source : Webster's Revised Unabridged Dictionary (1913)

Tylosis \Ty*lo"sis\, n.; pl. {Tyloses}. [NL., fr. Gr. ty`los a
   lump, knot.] (Bot.)
   An intrusion of one vegetable cell into the cavity of
   another, sometimes forming there an irregular mass of cells.
   --Goodale.