1. Rob,rifle,sack refer to seizing possessions that belong to others. Rob is the general word for taking possessions by unlawful force or violence: to rob a bank, a house, a train. A term with a more restricted meaning is rifle, to make a thorough search for what is valuable or worthwhile, usually within a small space: to rifle a safe. On the other hand, sack is a term for robbery on a huge scale during war; it suggests destruction accompanying pillage, and often includes the indiscriminate massacre of civilians: to sack a town or district.2. defraud, cheat.
late 12c., from Old French rober "rob, steal, pillage, ransack, rape," from West Germanic *rauba "booty" (cf. Old High German roubon "to rob," roub "spoil, plunder;" Old English reafian, source of the reave in bereave), from Proto-Germanic *raubon "to rob," from PIE *reup-, *reub- "to snatch" (see rip (v.)).
Lord, hou schulde God approve þat þou robbe Petur, and gif þis robbere to Poule in þe name of Crist? [Wyclif, c.1380]
To rob the cradle is attested from 1864 in reference to drafting young men in the American Civil War; by 1949 in reference to seductions or romantic relationships with younger persons. Related: Robbed; robbing.
Take from one to give to another, shift resources. For example, They took out a second mortgage on their house so they could buy a condo in Florida—they're robbing Peter to pay Paul. Although legend has it that this expression alludes to appropriating the estates of St. Peter's Church, in Westminster, London, to pay for the repairs of St. Paul's Cathedral in the 1800s, the saying first appeared in a work by John Wycliffe about 1382.