- to cast (goods) overboard in order to lighten a vessel or aircraft or to improve its stability in an emergency.
- to throw off (something) as an obstacle or burden; discard.
- Cards. to discard (an unwanted card or cards).
- the act of casting goods from a vessel or aircraft to lighten or stabilize it.
Origin of jettison
- to throw away; abandonto jettison old clothes
- to throw overboard
- another word for jetsam (def. 1)
Word Origin and History for jettisonable
1848, from jettison (n.) "act of throwing overboard" to lighten a ship. This noun was an 18c. Marine Insurance writers' restoration of the earlier form and original sense of the 15c. word that had become jetsam, probably because jetsam had taken on a sense of "things cast overboard" and an unambiguous word was needed for "act of throwing overboard."
Middle English jetteson (n.) "act of throwing overboard" is from Anglo-French getteson, from Old French getaison "act of throwing (goods overboard)," especially to lighten a ship in distress, from Late Latin iactionem (nominative iactatio) "act of throwing," noun of action from past participle stem of iectare "toss about" (see jet (v.)). Related: Jettisoned.