Guillotine: A machine used during (and after) the French Revolution for beheading people condemned to death, by means of a heavy sharp blade that slid down within vertical guides. By extension, "guillotine" refers to any shearing machine or instrument (such as a paper cutter, a book trimmer, etc.) that is like a guillotine in its action.
The word "guillotine" is named for a French physician, Joseph Ignace Guillotin (1738-1814). Appalled by the cruel methods (such as torture) by which people were then executed, Dr. Guillotin argued before the French National Assembly in 1789 that painless and private beheading by machine should become the standard means for capital punishment in a civilized society such as in France.
The National Assembly endorsed Dr. Guillotin's proposal on March 20, 1792. But, much to the doctor's dismay, the guillotine came almost immediately into public use and great abuse. The use of the guillotine was only abolished in France on October 9, 1981. The humanely-oriented Dr. Guillotin's name had long since become inextricably associated with the use of his machine.