1. a chemical compound used in dyeing, water purification, and medicine
Usage: chemistry
2. a graduate or former student of a particular school or university
Usage: informal; short for alumnus/alumna

Examples

• The water treatment plant uses alum to remove impurities.
• Alum is commonly used as a mordant in textile dyeing.
• She’s an alum of Harvard University.
• The college invited several distinguished alums to speak at graduation.
• As a recent alum, he still felt connected to his alma mater.
• The chemistry lab stored alum crystals in sealed containers.