Late Middle English: perhaps a modification of sup¹, as symbolic of a less vigorous action.

• sop from Old English:

  The Old English word sop first meant ‘to dip bread in liquid’—Chaucer says of his Franklin ‘Wel loved he in the morn a sop in wyn’—but nowadays a sop is something you do or offer as a concession to appease someone. This was originally used in the phrase a sop to Cerberus, referring to the monstrous three-headed watchdog which, in Greek mythology, guarded the entrance of Hades. In the Aeneid Virgil describes how the witch guiding Aeneas to the underworld threw a drugged cake to Cerberus, which allowed the hero to pass the monster in safety. When soppy, which comes from sop, first appeared in English in the early 19th century it meant ‘soaked with water’, not tears, as you might expect today from a feeble, sentimental soppy person. The writer H. G. Wells was one of the first to use the word in this sense. Soup (Middle English) comes from the French form of the same word. The American from soup to nuts for ‘from beginning to end’ dates from the early 20th century, while in the soup, also originally American and a variant of being in hot water is slightly earlier. Sip (Old English), sup (Old English), and supper (Middle English) go back to the same root.