In the traditional color wheel used by painters, violet and purple are both placed between red and blue. Purple occupies the space closer to red, between crimson and violet. Violet is closer to blue, and usually less intense and bright than purple.

While the scientific definition is clear, the cultural definitions are more varied. The color called purple by the French, pourpre, contains more red and half the amount of blue of the color called purple in the United States and the U.K. In German, this color is sometimes called Purpurrot ("purple-red") to avoid confusion.

In the Roman Republic, the togas of all citizens were bordered with a purple stripe. During a triumph, the general being honored wore an entirely purple toga bordered in gold. The commander of the army wore a purple cloak, called a paludamentum. During the Roman Empire, purple was reserved for the Emperors. The Emperor Caligula had a the King of Mauritania assassinated for wearing a purple mantle better than his own. Nero made it punishable by death for anyone else to wear the color.