It is believed that the symbol traces its origins to the symbol , an abbreviation of the Roman term "libra pondo", which translates as "pound weight". This abbreviation was printed with a dedicated ligature type, with a horizontal line across, so that the lowercase letter would not be mistaken for the numeral . Ultimately, the symbol was reduced for clarity as an overlay of two horizontal strokes "=" across two slash-like strokes "//". Examples of it being used to indicate pounds exist at least as far back as 1850.