Browlock is a portmanteau of “browser” and “lock”. This term is used either (1) to describe the state of an internet browser when the user is unable to perform certain actions or (2) to pertain to a malware’s malicious control over browser windows. A browlock can close the open tab or window, block access to the desktop of the system, and stop you from navigating to another site. For more information, see this blog post on browser lockers.