1. things that come before and indicate the approach of something else
Usage: plural form of precursor
2. substances from which other substances are formed
Usage: scientific context; plural form of precursor

Examples

• Dark clouds are often precursors to thunderstorms.
• The economic indicators served as precursors to the recession.
• Scientists studied the chemical precursors needed for the reaction.
• These early symptoms are precursors to the disease.
• The protests were precursors to major political changes.
• Amino acids are precursors to proteins in the body.
• The invention was one of the precursors to modern technology.