shill

Unknown; attested as verb 1914, as noun 1916. Perhaps an abbreviation of shillaber, attested 1913. The word entered English via carny, originally denoting a carnival worker who pretends to be a member of the audience in an attempt to elicit interest in an attraction.

Speculatively an extended form of German Schieber (“black marketeer, profiteer”) via *shi-la-ber.

There are some suggestions that it originates in the surname Shilaber or Shillibeer, especially George Shillibeer, but proposed origins are dubious as the word is first attested in North America in the 20th century, while proposed models are 19th century British.

American humorist Benjamin Penhallow Shillaber (1814–1890) was known to write under the name Mrs. Ruth Partington to lend credibility to some of his ideas. This is one more possible origin of the word, although there is no specific evidence supporting a connection.