sudden, abrupt, unexpected, improvised, offhand / suddenly serious (said of an illness; most often in the construction にわかになる (niwaka ni naru)) / temporary, makeshift, impermanent, ad hoc

(weaponry) uchigatana: a Japanese samurai sword, a descendant of the tachi.

exhaust pipe (pipe that vents waste gases from the engine)

vacate, leave / abandon (to relinquish a claim to property), surrender