"Telework" is a synonym for telecommuting, which refers to a working arrangement or work style where an employee regularly does his or her work off-site, or outside of the principal office. Teleworkers typically work from home one or more days a week and communicate with the office using telephones and over the Internet.
The US Office of Personnel Management (OPM) and General Services Administration (GSA) use the term "telework" for Federal Government reporting purposes and regarding all policy and legislative matters. Their Telework Guide defines telework as:
work arrangements in which an employee regularly performs officially assigned duties at home or other work sites geographically convenient to the residence of the employee
To be considered a teleworker, the employee has to work remotely at least once a month.
Note: telework, like telecommuting, does not refer to situations where employees sometimes take work home with them or where an employees's job involves a lot of off-site work or travel (e.g., sales).