Askirt that tapers gently out from a narrow waist, or a dress that grows gradually wider from the shoulder to the hem, is called an A-line, simply because its shape resembles the letter A. Though the tapered silhouette has been used during various fashion periods, it is generally agreed that the A-line dress became a staple of most women's wardrobes in the 1960s, just as styles were becoming simpler.
The modern A-line silhouette, or shape, was first seen during the mid-1950s, as part of French designer Christian Dior's (1905–1957) New Look. The New Look was a very feminine style, with sweeping