2.adjectiveDisposable; intended for a single use prior to being discarded.
"As the film opens, a martial-drum-dominated version of the "Star Wars" theme and the inevitable bottom-to-top print crawl inform us that the Clone Wars, a conflict that originated as a throwaway line in the original 1977 film... http//www.nysun.com/arts/star-wars-clone-wars-painted-in-the-stars/83922/"
3.adjectiveExtemporaneous; off the cuff.
"The host made a throwaway remark about the president that was later repeated on the television news."
4.adjectiveSelected or used without care or attention.