c. 1400, "a blow, stroke," perhaps originally imitative of the sound. Meaning "light tap with hand" is from c. 1804. Sense of "that which is formed by patting" (as in pat of butter) is 1754, probably from the verb. Pat on the back in the figurative sense "gesture or expression of encouragement, sympathy, etc." is attested by 1804.
"vessel in which cream or milk is agitated to separate it and make butter," Old English cyrin, from Proto-Germanic *kernjon (source also of Old Norse kirna, Swedish kärna, Danish kjerne, Dutch karn, Middle High German kern); probably akin to cyrnel "kernel" (see kernel) and describing the "grainy" appearance of churned cream.
1610s, "small sweet cake made of ground almonds (instead of flour) and whites of eggs," from French macaron (16c.), from dialectal Italian maccarone, the name of a kind of pasty food made of flour, cheese, and butter (see macaroni). The French meaning is said to have been introduced 1552 by Rabelais. The -oon ending was conventional in 15c.-17c. English to add emphasis to borrowings of French nouns ending in stressed -on.
"a mixture of liquids insoluble in one another, where one is suspended in the other in the form of minute globules," 1610s, from French émulsion (16c.), from Modern Latin emulsionem (nominative emulsio), noun of action from past participle stem of emulgere "to milk out," from assimilated form of ex "out" (see ex-) + mulgere "to milk" (from PIE root *melg- "to rub off; to milk"). The fat (butter) in milk is the classic example of an emulsion, drops of one liquid dispersed throughout another. Sense in photography is by 1840.
c. 1600, "reward given for a specific act or a particular line of conduct," from Latin praemium "reward, profit derived from booty," from prae "before" (see pre-) + emere "to buy," originally "to take" (from PIE root *em- "to take, distribute").
The sense of "amount to be paid by agreement for a contract of insurance" is from 1660s, from Italian premio. The adjectival sense of "superior in quality" is first attested 1925, originally in reference to butter. Figurative use of the phrase at a premium "at more than the usual value" is by 1828.
"conventional, complacent, materialistic American businessman," 1923, from the name of the title character of Sinclair Lewis' novel (1922).
His name was George F. Babbitt. He was forty-six years old now, in April 1920, and he made nothing in particular, neither butter nor shoes nor poetry, but he was nimble in the selling of houses for more money than people could afford to pay. [Sinclair Lewis, "Babbitt," 1922]
Earlier the name was used in metallurgy (1857) in reference to a type of soft alloy (1875).