Curtains are called blinds because when they are closed you are blind to the outside

Nice try, but unfortunately no. Blinds are based on the old 'shutters', which were made of either metal or wood. You probably know what I'm talking about - you still see them on some older homes and in 19th century period pieces. When the quality of home windows got better, heavy shutters were not as necessary. Additionally, the cost of curtain material had gone down at around the same time. People wanted the familiar shutter-style, but made out of curtain cloth - hence the creation of the 'blinds'.

However, at this time they were still being referred to as 'shutters' (this was the standard British term; the fad had only caught on overseas among the very wealthy, who saw it as 'couture'). These curtain-shutters became very popular throughout Europe, including Germany. Fast-forward several decades later during the height of Nazi Germany. Isla Koch, the wife of a concentration camp commander, had been kidnapping prisoners from the Buchenwald concentration camp, torturing and killing them, and using their skin to create furniture - thus, her common moniker "The Butcher of Buchenwald". For her curtain-shutters she had specifically used the skins from people she had blinded during torture.

During her trial after WWII she consistently referred to her curtain-shutters as Getinunderdiescheisserei, which literally translates to 'Blinds'. One of the magistrates sitting on these war crimes tribunals was Judge Franklin Woolsworth, who upon his return to the United States opened the well-known, but unfortunately short-lived, Woolsworth Co. housewares and furniture retail chain. One of their headlining products for the general market was this curtain-shutter that had long been popular in Europe, but as a result of his participation in the 'Butcher of Buchenwald' trial he had become accustomed to calling them 'Blinds' and advertised them this way. What he didn't realise is that, while the German term does indeed mean 'blinds' in the sense of blind people, it carries the particular connotation that those people were purposely blinded as a form of torture. By the time that German-Americans had brought this mistake to the media's attention in the mid 1960s it was too late: the term 'Blinds' had caught on.

And the rest is history.

/r/Showerthoughts Thread