Tights were a kind of cloth leg garment, most often sheathing the body from above the waist to the feet with a tight fit, hence the name. Though primarily worn by women, they were also commonly worn by men in eras such as the Middle Ages.
When Starkey, a native of 2050, asked a virtual reality simulation of Robin Hood, "What's with the tights?", he replied that it was the fashion of the time and that it was chilly. K9 confirmed that Britain was on average three degrees colder in the Middle Ages. (TV: The Last Oak Tree)