derivations puzzles answers

Original meanings and derivations for words and expressions:

1. scuba (diving) - it's an acronym for 'self-contained underwater breathing apparatus'.
2. biscuit (snack food) - from the Latin and French 'bis' (twice) and 'cuit' (baked), because this is how biscuits were originally made, ie., by cooking twice. The term is found also in pottery and ceramic glazing for the same reason.
3. sold down the river (exploited or betrayed for profit) - from the American slave trade 1620-1863, and particularly during the 1800's, after the abolition of the slave trade across the Atlantic and the increasing resistance against slavery in the northen USA, slaves were literally 'sold down the river' (typically The Mississippi) to the cotton producing heartlands of the southern states.
4. put a sock in it (shut up) - from the days before electronic hi-fi, when wind-up gramophones (invented in 1887) used a horn to amplify the sound from the needle on the record; the common way to control or limit the volume was to put a sock on the horn, thus muting the sound. The practice was still common in the 1930's.
5. red tape (bureaucracy) - from the middle-to-late English custom for lawyers and government officials to tie documents together with red tape. The term was first used metaphorically to describe official formality by Charles Dickens (1812-70).
6. hip hip hooray (three cheers) - originally in common use as 'hip hip hurrah'; derived from the middle ages Crusades battle-cry 'Hieroslyma est perdita' (Jerusalem is fallen), and subsequently shortened by Germanic tribes when fighting Jews to 'hep hep', and used in conjunction with 'hu-raj' (a Slavic term meaning 'to paradise'), so that the whole phrase meant 'Jerusalem is fallen and we are on the way to paradise'.
7. hat-trick (three scores/wickets/wins) - from the game of Cricket in 18-19th century, when it was customary to award a bowler who took three consecutive wickets a new hat at the expense of the club. The word 'trick' has meant a winning set of three, particularly in card games, for hundreds of years.
8. velcro (cloth fastener) - velcro was invented in 1954 by George de Mestrel, having been inspired by Alpine burdock burrs which stick to cloth; he named the nylon fastening after velours crochet , French for 'velvet hook'.
9. bury the hatchet (agree to stop arguing) - from the native American Indian custom, as required by their spirit gods, of burying all weapons out of sight while smoking the peace pipe.
10. scot free (escape without punishment) - scot free (originally 'skot free') meant 'free of taxes', particularly tax due from a person by virtue of their worth. One who avoided paying their tax was described as 'skot free'. 'Scot and lot' was the full English term for this levy which applied from 12th to 18th century. Scot was derived from the Norse 'skot', meaning tax due from a tenant to his landlord; 'lot' meant the amount allotted. Less significantly, a 'skot' was also a slate in Scottish pubs onto which customers' drinks debts were recorded; drinks that were free were not chalked on the slate and were therefore 'skot free'. In the USA, the expression was further consolidated by the story of Dred Scott, a slave who achieved freedom, presumably towards the end of the slavery years in the 19th century, by crossing the border fom a 'slave state' into a 'free state'.