From ‘rīvus’, ‘a stream’, the Latin adjective ‘rīvālis’ (of, or belonging to, a stream) was used as a plural noun, ‘rīvāles’, to denote persons who have to use the same stream, and persons who have the same mistress, competitors in love.
mi-17th century—probably from ‘hand in (the) cap’, used of a sort of game in which players put forfeit money in a cap and then drew from it—later applied to a race between two horses (the better of which carried extra weight), arranged by such rules
British English, first recorded, apparently as army slang, in 1945—probably from ‘bonk’ (= a blow on the head) and the suffix ‘-ers’ as in ‘ravers’ (from ‘raving mad’) and ‘starkers’ (from ‘stark mad’)
First recorded in 1694, ‘Peg Tantrum’ was chiefly used in the phrase ‘to go to Peg Trantum’s’, meaning ‘to go to one’s death’. This word is perhaps from ‘Peg’, rhyming form of ‘Meg’, pet form of the female forenames ‘Margery’ and ‘Margaret’, and from ‘tantrum’.
Old English ‘werewulf’ (first element identified with Old English ‘wer’, ‘man’) first used for ‘wolf’ to denote a person serving Satan (cf. Gospel of Matthew “Beware of false prophets, who come to you in sheep’s clothing, but inwardly they are ferocious wolves”)
‘scruple’—from Latin ‘scrūpŭlus’, literally ‘a small sharp or pointed stone’—probably because such stones used to get into the open shoes of the Romans, ‘scrūpŭlus’ came to denote ‘a pricking, uneasy sensation’, hence ‘trouble’, ‘doubt’, ‘scruple’
UK, 1819—specifically invented to qualify the English poet and critic William Gifford with reference to the fact that he had been a shoemaker’s apprentice—alludes to the proverb ‘let the cobbler stick to his last’ from Pliny’s Natural History (AD 77)
A diminutive of ‘pūpa’ (‘a girl’, in transferred use also ‘a doll’), the Latin feminine noun ‘pūpilla’ came to also denote ‘the pupil of the eye’ on account of one’s own reflection seen when looking into somebody’s eye—the same metaphor underlies ‘to look babies in somebody’s eyes’.
Bing Crosby popularised ‘pennies from heaven’ in the 1936 film and song of the same name, but the phrase already existed; and Abraham Burstein, rabbi and author, had used ‘pennies falling from heaven’ in The Ghetto Messenger in 1928.
‘Magazine’ (= ‘storehouse’) came to denote a book providing information on a specified subject (17th c.). This gave rise to the sense ‘periodical magazine (= ‘repository’) of the most interesting pieces of information published in the newspapers’ (18th c.).