The Collaborative International Dictionary
Metabasis
Metabasis \Me*tab"a*sis\, n.; pl. Metabases. [NL., fr. Gr. ?, fr. ? to pass over; ? beyond, over + ? to go.]
(Rhet.) A transition from one subject to another.
(Med.) Same as Metabola.
Wiktionary
metabasis
n. 1 (context rhetoric English) A change from one subject to another. 2 (context pathology English) Any change in the course of a disease; metabola.