What is the origin of alma mater?

Alma mater “a school where one has studied” comes from a Latin phrase that means “nourishing mother.” The first half, alma “nourishing” or “kind,” derives from an Indo-European root appearing variously as al-, el-, ol-, or ul- that is found frequently in words connected to nourishment or, more generally, the life cycle. Alumnus means “nourished one” in Latin, while alimony derives from the noun alimōnia “feeding” or “nourishment,” and the verb coalēscere, the source of coalesce, literally means “to grow up together.” Adolescent and adult come from the same Latin verb, adolēscere, and respectively mean “becoming mature” and “having matured,” and prolific and proliferate derive from prōlēs “offspring.” This same Indo-European root found in alma appears in English as well, in words such as old, elder, and alderman, and in the Scots phrase auld lang syne.