An alumnus is someone who attended or graduated from a particular school, college, or university. The word comes from Latin and originally meant “foster son” or “pupil.”

When your older sister graduates from high school, she becomes an alumna of that school. When someone mentions they're an alumnus of Stanford University, they're saying they studied there. Schools often stay connected with their alumni (the plural form), inviting them back for reunions, asking them to mentor current students, or requesting donations to support the school.

The word changes based on gender and number in its traditional Latin form: alumnus for one man, alumna for one woman, alumni for multiple people (or multiple men), and alumnae for multiple women. Many people today simply use alumni for any group of former students, regardless of gender. You might also hear people use alum as a shorter, informal version that works for anyone.

Schools take pride in their successful alumni. When a famous scientist, artist, or leader credits their education at a particular school, that person becomes a celebrated alumnus whose achievements reflect well on everyone connected to that institution.