What's the origin of "pigtails"?
Dear Straight Dope:
Where do they get the term "pigtails" since there aren't two tails or a split?
The first use of the term pigtail was, of course, to refer to the tail of a pig. By the mid-1600s, however, it had taken on the added meaning of tobacco twisted into a thin string (that looked like a pig's tail.)
From there, the term was used to describe a "plait or queue of hair hanging down from the back of the head," especially for sailors and soldiers, in the late 18th and early 19th century. The Oxford English Dictionary cites this usage as early as 1750s. Usually, it was just one pigtail. The further and later nautical use of pigtail refers to a short length of rope (1894.)
The term was also used as a derogatory reference to Chinese in the late 1800s. The pigtail was a mark of political enslavement to the Manchu dynasty, and westerners made fun of the Chinese hair style. The pigtail was abolished in China in 1911 when the Manchu dynasty was overthrown in favor of the Republic.
The term used for one braid was then obviously applied (in plural) to the hairstyle of two braids.