Alumna: Feminine, Singular Noun
Used when referring to a female who is a graduate of a particular school, college, or university.
Cathey Boggs, an alumna who lives in Ohio, serves on the Ball State University Alumni Council.
Alumna Cynda Williams has appeared in several motion pictures.
Alumnae: Feminine, Plural Form
Used when referring to a group of female graduates of a particular school, college or university.
Ball State alumnae from 30 states attended the sorority reunion in August.
Twenty-five alumnae have been Homecoming queen.
Alumnus: Masculine, Singular Form
Used when referring to a male who is a graduate of a particular school, college or university.
David Letterman is an alumnus of Ball State University.
Alumnus Jim Davis is the creator of Garfield.
Alumni: Plural Form
Used when referring to a group of males or a group of both male and female, who are graduates of a school, college or university.
During Homecoming, alumni will be honored with awards for their distinguished service to their professions and the nation.
A large number of Ball State alumni live in the Michiana area.
Alum—A double sulfate of ammonium or a univalent metal (as sodium or potassium) and of a trivalent metal (as aluminum, iron or chromium).
Alum is used as an astringent, as an emetic, and in the manufacture of baking powders, dyes and paper.
Webster's Dictionary also lists alum as an Americanized colloquial form of "alumnus" or "alumna." (Alum/alums is not a preferred usage by the Ball State University Alumni Association.)
Ball State University Alumni Association will, according to the Associated Press Stylebook, use alumnus/alumna or alumni/alumnae to indicate an attendee/graduate of the University. In instances where the gender is not known, the individual/group will be referred to the Merriam-Webster Dictionary general reference of alumnus/alumni to be non-gender specific.
The "definition" of alumnus/alumna status varies from school, college or university. At Ball State an individual is considered an alumnus/alumna after attending one term.