hash3
Pronunciation: /haʃ/
(also hash sign)
Origin:
1980s: probably from hatch3, altered by folk etymology
The symbol #, called hash in British English, has different names, some of them potentially confusing. In the US it is referred to as either the number sign (when used in contexts such as question #2) or the pound sign (when used as a symbol for pounds of weight, e.g. 2# of sugar). The technical name for it is the octothorp.