1. Plural of phlogiston; a hypothetical substance once believed to be present in all combustible materials and released during burning (historical chemistry theory, now discredited).
Usage: archaic; historical; chemistry

Examples

• Eighteenth-century chemists theorized that phlogistons were released when wood burned.
• The phlogiston theory was eventually replaced by the modern understanding of oxidation.
• Scientists once believed phlogistons explained why some materials burned more readily than others.
• The concept of phlogistons is now considered a discredited scientific hypothesis.
• Early experiments with phlogistons led chemists to develop better methods for studying combustion.