Final answer:
The meter was originally defined by French scientists in the 17th and 18th centuries as one ten-millionth of the Earth's quadrant, evolving over time to a definition based on the speed of light in a vacuum.
Step-by-step explanation:
The famous French scientist who defined the meter is not attributed to a single individual but to a group of French astronomers and scientists from the seventeenth and eighteenth centuries. The meter was originally defined during the French Revolution with a scientific basis being the distance along Earth's surface from the equator to the pole, specifically one ten-millionth of this distance. This was part of the broader adoption of the Metric System, officially endorsed in France in 1799, during the time of Napoleon.
The definition of the meter has evolved over the years to increase precision. In 1889, a platinum-iridium bar was stored in Paris to serve as the physical standard for the meter. The meter definition was revised again in 1960 and 1983 with the advancements in technology, moving from physical objects to specific atomic transitions and eventually to the distance light travels in a vacuum in a definitive fraction of a second.