Bail is an old word from the early 15th century from the French baille for bucket or pail. Bail as in, to bail water from a boat dates from the early 17th century. Presumably, one used a bucket to do this, hence the association with the meaning just referred to. Bail as in bond money put up for the temporary release of someone from custody is from the 15th century and is from a different etymological route, this time the Old French baillier meaning to guard or protect from which we get words like bailiff and bailiwick. The pieces of horizontal wood on the top of cricket stumps are also called bails (c.1742) and this derives from the Medieval French bail meaning the horizontal piece of wood at the top of two wooden poles. Bail as in, bail out of an aircraft is from c.1925 and possibly reflects the bailing of water out of a boat. The more figurative notion of a financial bail-out is first recorded c.1955, while bailing out of a situation or walking away from something as in, ‘I was not enjoying the party, so I bailed’ is American and dates from the 1970s.