swap

Etymology 1

From Middle English swappen (“to swap”), originally meaning "to hurl" or "to strike", the word alludes to striking hands together when making an exchange; probably from Old English *swappian, a secondary form of Old English swāpan (“to swoop”). Cognate with German schwappen (“to slosh, slop”). Compare also Middle English swippen (“to strike, hit”), from Old English swipian (“to scourge, strike, beat, lash”), Old Norse svipa (“to swoop, flash, whip, look after, look around”). More at swipe.

verb

1. (transitive) To exchange or give (something) in an exchange (for something else).
   In an effort to provide more permanent accommodations, employers may offer employees the opportunity either to swap jobs with a colleague or to transfer to a new position. 1998, Michael Wolf, Bruce Friedman, Daniel Sutherland, Religion in the workplace, page 98
   Chief watched these goings-on without pleasure, and waved them off in disgust when the smarmiest of the two suggested he might wish to swap that elk's tooth for this jug of fine rye whiskey. 2007, Lloyd Zimpel, A Season of Fire and Ice
   The Shah wanted to swap oil for more arms. 2011, Andrew Scott Cooper, The Oil Kings: How the U.S., Iran, and Saudi Arabia Changed the Balance of Power in the Middle East, page 253
2. (transitive, obsolete) To hit, to strike.
   And he whipped his sword out of its scabbard, and swapped off the pudding from the black knight's nose. Unfortunately (for him) he swapped off a good bit of the nose, too. 1954, Edward Eager, Half Magic
   "Maybe Apes will grow honest, Sister," said Edmund. "But, by the Lion, if he breaks it again, it may be in such time and place that any of us could swap off his head in clean battle." 1954, C. S. Lewis, The Horse and His Boy
3. (transitive, obsolete) To beat the air, or ply the wings, with a sweeping motion or noise; to flap.
4. (intransitive, obsolete) To descend or fall; to rush hastily or violently.

Etymology 2

From the verb swap. First attested in 1620.

noun

1. An exchange of two comparable things.
   I e’en changed it, as occasion served, with the skippers o’ Dutch luggers and French vessels, for gin and brandy[…] a gude swap too, between what cheereth the soul of man and that which dingeth it clean out of his body 1819, Sir Walter Scott, Tales of My Landlord, The Bride of Lammermoor
2. (finance) A financial derivative in which two parties agree to exchange one stream of cashflow against another stream.
3. (computing, informal, uncountable) Space available in a swap file for use as auxiliary memory.
   How much swap do you need?
4. (Cambridge University slang) A social meal at a restaurant between two university societies, usually involving drinking and banter; commonly associated with fining and pennying; equivalent to a crewdate at Oxford University.

Etymology 3

From Middle English swap, swappe (“a blow, strike, lash from a whip”), from the verb (see Etymology 1 above).

noun

1. (obsolete, UK, dialect) A blow; a stroke.