Shares which are held by a person in his or her name, but are really owned on behalf of someone else (who is also known as the beneficial owner). That someone else is said to be an indirect shareholder.

Or:

What is indirect ownership?
A person is an indirect beneficial owner when the person's securities are held through an issuer, an affiliated issuer, a family trust, a third person
or other legal entity. Securities beneficially owned but held through a nominee such as a broker or book-based depository are considered direct
holdings.
Example: The insider is the indirect beneficial owner of securities that are held by a holding company that an insider or its subsidiaries controls.
Whenever an insider is deemed to be the beneficial owner, the insider will be an indirect beneficial owner.