1. number sign; hash sign; pound sign
Wikipedia definition
2. Number signNumber sign is a name for the symbol #, which is used for a variety of purposes including, in some countries, the designation of a number (for example, "#1" stands for "number one"). The symbol is defined in Unicode as U+0023 # number sign; it is also present in ASCII with the same value. In Commonwealth English, the symbol is usually called the hash and the corresponding telephone key is called the hash key.
Read “Number sign” on English Wikipedia
Read “番号記号” on Japanese Wikipedia
Read “Number sign” on DBpedia


to talk about this word.