zero prefix

Etymology
From 🇰🇲.

Noun

 * 1)  The digit 0 that begins all telephone numbers in the United Kingdom, which is substituted for the country code in the event of international calls.
 * 2)  A prefix which is a null morpheme, used in models of linguistic analysis to represent the lack of a prefix where one might otherwise be expected (for example, as one of several inflections that a stem can take, or the reduction of a historically vocalised prefix to the point that it is inaudible).