1. existing in a relatively stable state that can change to a more stable state under certain conditions
Usage: physics; chemistry

Examples

• The metastable isotope eventually decayed into a more stable form.
• Water can exist in a metastable supercooled state below its freezing point.
• The metastable phase of the material lasted for several hours before transitioning.
• Scientists studied the metastable configuration of the atomic nucleus.
• The metastable compound remained unchanged until heated to a higher temperature.
• Diamond is actually metastable compared to graphite under normal conditions.