Administrator and Sysop are the technical names used on many wiki-based sites to refer to contributors who have the technical privileges to make certain important changes to pages and user accounts, and also view information that is hidden from ordinary users. Someone who controls a user account within the Citizendium sysop group, which is labelled 'Administrators' for convenience, may delete and lock most pages, block accounts to prevent editing, create new accounts, view the IP addresses of users, and carry out various other procedures.
On Citizendium, the term 'sysop' is not used much because it is uninformative and because sysop rights are shared between various people depending on their roles. 'Administrator' is preferred. Moderators have Administrator powers. So too do technical staff. Other people may also have Administrator rights in order to carry out various duties. A few also have extra rights.
Administrator powers are granted to trusted individuals based on a decision by the Citizendium Council. The privileges are handed out sparingly; Council members and even the Managing Editor are not given Administrator rights by virtue of holding office.