Is it acceptable to use alum for alumnus or alumna?

The words that we have used to refer to people who have attended or graduated from a school, college, or university have changed a bit over the past several centuries. Traditionally, the word alumnus has been used to refer to a single male, whereas alumna has been used for a single woman. Initially the plural forms were alumni to refer to multiple men (or multiple men and women) and alumnae for multiple women. A little over a hundred years ago the shortened form of alum began to be used to describe a graduate or past attendee of either gender. Although many people feel that alum is informal, it is in increasing use, and we appear to be moving toward a greater acceptance of the word. The plural of alum is alums.