= "analogue-to-digital converter".
Apparently an isolated use.
2Frequently in form DigiBox. Computing. A digital envelope allowing the transmission of data in encrypted form, especially across the internet, together with codes which allow access only to users who comply with the stated conditions of use.
A trademark in the United Kingdom.
3An electronic device that can be plugged into a domestic analogue television to enable it to receive digital signals.
1990s; earliest use found in Usenet (newsgroups). From digi- + box.