the.com/alum

means A former student or graduate of a particular school, college, or university — shortened from 'alumnus' or 'alumna.'

from From Latin alumnus, meaning 'foster son' or 'pupil,' itself rooted in alere, 'to nourish or feed.' The same root gives us 'alimony' and 'aliment' — all tied to the idea of being nursed or raised up. The informal clip to 'alum' is a modern convenience, sidestepping the Latin headache of alumnus/alumna/alumni/alumnae depending on gender and number. The mineral sense is a completely different word, from Latin alumen — a coincidence of spelling, not a shared ancestor, which is why the 'essence' pun is a pun and not etymology.