What is Gag Order?

Legal Definition
A gag order (also known as a gagging order or suppression order) is an order, typically a legal order by a court or government, restricting information or comment from being made public or passed onto any unauthorized third party. The phrase may sometimes be used of a private order by an employer or other institution.

Gag orders may be used, for example, to keep legitimate trade secrets of a company, to protect the integrity of ongoing police or military operations, or to protect the privacy of victims or minors. Conversely, as their downside, they may be abused as a useful tool for those of financial means to intimidate witnesses and prevent release of information, using the legal system rather than other methods of intimidation. Strategic Lawsuit Against Public Participation (SLAPP) orders may potentially be abused in this way.

Gag orders are sometimes used in an attempt to assure a fair trial by preventing prejudicial pre-trial publicity, although their use for this purpose is controversial since they are a potentially unconstitutional prior restraint that can lead to the press's using less reliable sources such as off-the-record statements and second- or third-hand accounts.

In a similar manner, a "gag law" may limit freedom of the press, by instituting censorship or restricting access to information.
-- Wikipedia
Legal Definition
an order given by a court that restricts any information that is about a case that is pending.