USA, 1811—based on the three principal components that make up a flintlock gun: ‘lock’ denotes the firing mechanism, ‘stock’ the handle or wooden shoulder-piece to which it is attached, and ‘barrel’ the tube down which the bullet is fired
16th century—from the Latin adjective ‘praeposterus’, composed of the adverb ‘prae’ (‘in front’, ‘before’) and the adjective ‘posterus’ (‘coming after’, ‘following’, ‘next’), so that its literal sense is ‘next (placed) first’, ‘having first what should be coming after’.
from the name of Mrs Malaprop, a character who confuses long words in The Rivals (1775), a comedy by the Irish playwright Richard Brinsley Sheridan—character named after ‘malapropos’, from the French locution ‘mal à propos’, literally ‘ill to purpose’
‘eggcorn’: alteration of a word or phrase through the mishearing or reinterpretation of one or more of its elements as a similar-sounding word—coined in 2003 on the website Language Log with reference to a misinterpretation of ‘acorn’ as ‘eggcorn’
from the 16th-century phrase ‘to set cock a hoop’, ‘to set (the) cock on (the) hoop’, apparently meaning ‘to put the cock (= spigot) on a barrel hoop and let the liquor flow prior to a drinking bout’—‘cock’ later equated with the fowl and ‘hoop’ with French ‘huppe’ (tufted crest)
The phrase ‘all behind, like a cow’s tail’ and its variants mean ‘left behind’ and ‘late in accomplishing a task’. They appeared in print in the mid-19th century in the USA, Australia and Britain.
‘to take the Fifth’: to decline to reveal one’s own secrets—from ‘to take the Fifth Amendment’: to appeal to Article V of the original amendments to the U.S. Constitution, which states that “No person […] shall be compelled in any criminal case to be a witness against himself.”
‘Sydney or the bush’: all or nothing (1902)—based on the metaphorical opposition between an easy life in the city and a hard life working in the outback, this phrase was apparently originally used by people risking all on the toss of a coin.
‘dunce’: originally a follower of John Duns Scotus (circa 1265-1308), scholastic theologian; in the 16th century, Scotus’s system was attacked with ridicule by the humanists and the reformers as a farrago of needless entities and useless distinctions
UK, early 19th century—private property taken from an enemy in war—originally an Anglo-Indian noun, from Hindi ‘lūṭ’, from Sanskrit ‘luṇṭh-‘, ‘to rob’—came to be also used as slang for ‘money’ and to also denote ‘wedding presents’