middle initial

middle initial (plural middle initials)

1. An abbreviated middle name.
2. (Philippines, by extension) The abbreviated form of the last name of one's mother.

My full name is Ma. Clara Teresita R. dela Cruz. My mother's last name is Rodriguez.

• In the Philippines, this is only used in reference to one's complete legal full name, since people normally use a shortform full name composing only at least one of their primary given names (usually their first name) together with their last name (father's surname).