The school you graduated from is your alma mater. ----
Alma mater means nourishing mother in Latin. So the school or college which nourished you spiritually is your alma mater.
an alma mater
All of the graduates participated in singing the school's Alma Mater at graduation, as to show their appreciation and pride in their school.Tom: "Hey Jane, where did you graduate from high school?"Jane: "Oh, Central High School is my alma mater."
Alma mater
alma mater
The Tagalog word for alma mater is "pinanggalingan" or "pamantasan."
Alma mater (Latin: "nourishing mother")
Who wrote the alma mater Southern sun and sky blue water Smile upon you alma mater
The school or college from which one graduates is called one's alma mater.
Atwater High our Alma mater Loyal sons are we Proud to service in thy name True to thee we'll be Faithful, loyal, firm and true Though from you we'll stray Atwater High our Alma mater Loyal sons we'll stay
Nowadays term 'alma mater' doesn't refer to a person, but a school, so it would be Hogwarts.