RhymeZone: katabasis definitions

Definitions of katabasis:

noun: (mythology, literature) A mytheme or trope in which the hero embarks on a journey to the underworld.
noun: (by extension, humorous) Any journey downwards or fall.
noun: A retreat, especially a military one.
noun: A journey from the interior of a country to the coast.
noun: (rare) The presence of downward (drainage or katabatic) winds.

(Definitions from Wiktionary)