Traditionally, "alumnus" refers specifically to a singular male graduate and "alumni" is the plural form for a group of male graduates and for a group of male and female graduates. Meanwhile, the term for singular female graduates is the lesser spotted "alumna", and "alumnae" refers to a group of female-only graduates.

This isn't the place to start scrutinising the gender bias that's ingrained in certain languages, tempting though it is. We'll focus on what we think is the most acceptable way to approach it in content:

1. Avoid using these words as much as possible; use "graduate" or "postgraduate" instead (or "former pupil" if talking about a school).
2. If you really must use it, "alumni" is OK for the plural.
3. If you really really must use the Latin singular, use "alumnus" to refer to both male and female graduates.

Try hard to avoid using these words, because not only do they make things awkward when it comes to gender, but they also make us look old-fashioned and a bit elitist.