1. philosophers who believe that space cannot exist as a vacuum and must be filled with matter
Usage: philosophy; historical

Examples

• The plenists argued against the possibility of empty space in nature.
• Descartes and other plenists maintained that all space must contain some form of matter.
• The debate between plenists and vacuists shaped early modern physics.
• Plenists believed that a true vacuum was impossible to achieve.
• The plenists’ theories were eventually challenged by experimental evidence of vacuums.