Latin for 'foster children, the nourished ones' — graduates conceived as fed by their alma mater.
Former students or graduates of a particular school, college, or university (plural of 'alumnus'); broadly, former members of any institution or organization.
From Latin 'alumni' (plural of 'alumnus,' a foster child, a pupil, one who is nourished), from 'alere' (to nourish, to feed, to sustain), from PIE *al- (to grow, to nourish). The original Latin 'alumnus' was not a graduate but a foster child — someone nourished and raised by another. The educational sense developed because students were metaphorically 'nourished' by their alma mater (nourishing mother, i.e., the university). The feminine form 'alumna' (plural 'alumnae') is grammatically correct but increasingly replaced by the gender
An 'alumnus' is etymologically a foster child — someone nourished by an institution. The university is the 'alma mater' (nourishing mother), and its graduates are her nourished children. The same root gives us 'adolescent' (growing up), 'adult' (fully grown), and 'altitude' (height, growth upward).