1. a hypothetical primitive substance from which all chemical elements were thought to be formed
Usage: historical; chemistry

Examples

• The 19th-century chemist William Prout proposed that all elements were composed of protyle.
• Scientists once believed protyle was the fundamental building block of matter.
• The concept of protyle preceded our modern understanding of atomic structure.
• Prout’s hypothesis suggested that protyle was essentially hydrogen in different forms.
• The protyle theory was eventually disproven by more accurate atomic weight measurements.